WO2001083038A1

WO2001083038A1 - Detoxification of halogenated compounds in contaminated media

Info

Publication number: WO2001083038A1
Application number: PCT/NZ2001/000069
Authority: WO
Inventors: Bryan Geoffrey Black; Bianca Kuipers
Original assignee: Environmental Decontamination Limited
Priority date: 2000-05-03
Filing date: 2001-05-02
Publication date: 2001-11-08
Also published as: WO2001083127A1; AU6081701A; AU6081601A

Abstract

A method of reducing the level of at least one organo-halogen compound in and/or on a matrix is disclosed which comprises or involves milling the matrix with at least one organo-halogen compound in a ball mill with one or more of: (I) urea, (II) an iron sand, (III) steel makers slag, and/or (IV) a suitable acid.

Description

DETOXIFICATION OF HALOGENATED COMPOUNDS IN CONTAMINATED MEDIA

The present invention relates to the detoxification of halogenated organic compounds and particularly, but not solely, those in contaminated media. The invention also consists in related plant systems and methods as well as the decontaminated products or media.

BACKGROUND

Organo-halogen compounds are recognised as a problem in the environment. Many methods have been proposed whereby the levels of such troublesome organo-halogen compounds may be reduced.

One such approach was that disclosed in PCT/AU93/00660 (WO 94/14503) of Technological Resources Pty. Limited and The University of Western Australia. This process for the treatment of halogenated organic compounds (such as poly-chlorinated biphenyls (PCBs), dioxin, dichlorodiphenyl trichloroethane (DDT)) relies on mechanical activation to induce chemical reactions which break down the molecular structure of the toxic organo- halogen materials into forms which are simple and non-toxic. The process involved subjecting a mixture of the toxic materials and a suitable reagent inside a mechanical mill, for example, a ball mill. PCT/AU93/00660 indicates that suitable reagents may include oxidising agents such as iron oxide, manganese dioxide and oxygen. Alternatively it is suggest that the reagent may be a reducing agent such as aluminium metal, iron metal and zinc metal. Other suitable reagents mentioned include sodium hydroxide, graphite, red mud, lime or quicklime, water, carbon dioxide, calcium oxide, copper oxide, aluminium oxide and magnesium oxide. PCT/DE98/02787 (WO 99/15239) of V. Birke discloses a method for reductive dehalogenation of halo-organic substances in a manner similar to that mentioned previously but with a mixture of reagents. One is selected from elementary alkali metal, elementary alkaline earth metal, elementary aluminium and elementary iron and the other from compounds having an activated hydrogen as a hydrogen source. Preferred sources of hydrogen mentioned include alcohols, ethers, poly ethers, amines or hydroxides (eg; calcium hydroxide), metal hydrides or non-metal hydrides (eg; calcium hydride), sodium hydride, sodium boronate, lithium alanate, trialkylsilane, polyalkylhydrogensiloxane or combinations thereof. Specific amines mentioned (but not necessarily shown by reference to examples as being effective) include primary, secondary or tertiary aliphatic and alicyclic monamines or polyamines, methylamine, ethylamine, 1- and 2-propylamine, 1- and 2-butylamine, ethylene diamine, hi-, terra-, penta-, hexamethylene diamine, dimethylamine, diethylamine, di-n-propylamine, cyclopentyl- and cyclohexylamine, nitrogen heterocycles and perhydro nitrogen heterocycles, for example piperidine, l-(2-aminoethyl)-piperazine, l-(2-armnoethyl)-pyrrolidine and 1-2(2- aminoethyl)-piperidine, 4-(2-aminoethyl)-morpholine and liquid ammonia.

PCT/DE98/02787 indicates as a possible alternative to the amines certain amides can be considered. There is disclosure of the following amides as possible alternatives: 1,3 dimethyl-3,4,5,6-tetrahydro-2(lH)-pyrimidon (dimethylpropylene urea, DMPU), 1,3- dimethyl-2-imidazolidinon (N,N-dimethylethylene urea, DMEU), l-methyl-2-pyrrolidon (NMP), l-ethyl-2-pyrrolidon, N,N-diethylacetamide, N,N-diethylpropionamide, N,N- diethylisobutyramide. However no supporting data showing their effectiveness is included.

Specific examples given in PCT/DE98/02787 relate to PCB ' s, chlophen and 1 ,3 ,5-TCB only. No example is given of any dehalogenation of the persistent organo-halogen compounds dichlorodiphenyl trichloroethane (DDT or DDE), and Dieldrin. Indeed our own experimentation utilising procedures such as disclosed in PCT/DE98/02787 has failed to show an acceptable reduction in the levels of, for example, DDT, DDE and/or Dieldrin in contaminated soils where, as suggested, an elementary metal (eg; magnesium) is utilised in conjunction with, for example, calcium oxide or an amine such as butylamine.

Moreover, where a persistent organo-halogen contamination in, for example, a media such as soils exists, and there is a large volume of soil to be treated, it is imperative to ensure that whatever reagents are utilised can be economically utilised. It is imperative therefore to provide reagents not only relatively cheap and commonly available but also capable of being used effectively in required quantities with the particular contaminated soil to be treated. Otherwise unnecessarily heavy plant and higher energy costs may become involved.

STATEMENT OF INVENTION

Accordingly in a first aspect the present invention consists in a method of reducing the levels of an organo-halogen compound which involves the milling (single, simultaneous or sequential) of the compound (eg; when in a contaminated media) in the presence of one or more of:

(I) urea with a suitable metal source,

(II) a suitable iron sand with a suitable amide,

(III) a suitable iron sand with a suitable acid,

(IN) a suitable iron sand with a suitable hydrogen donor, (V) a suitable iron sand with a suitable acid and a suitable amide,

(VI) a suitable iron sand with a suitable acid and a suitable hydrogen donor, (Nil) urea,

(NIII) urea with a suitable acid, (IX) urea with a suitable acid and a suitable metal source,

(X) steel makers slag,

(XI) steel makers slag with a suitable amide,

(XII) steel makers slag with a suitable acid,

(XIII) steel makers slag with a suitable acid and a suitable amide, (XIN) steel makers slag and urea, and

(XN) steel makers slag, urea and a suitable acid.

In another aspect the present invention consists in a method of reducing the level of at least one organo-halogen compound in and/or on a matrix which comprises or involves milling the matrix with the at least one organo-halogen compound in a ball mill with one or more of a) urea, b) an iron sand, c) steel makers slag, and/or d) a suitable acid. Preferably urea is used and preferably with an iron sand or steel makers slag.

Preferably the energising of the ball mill is such that a temperature of at least about 70 °C is generated in the ball mill mix.

Preferably said ball mill is of a kind with ferrous balls and/or a ferrous ball confinement chamber. By "ferrous" is meant iron or steel or some alloy which includes iron.

Preferably said organo-halogen compound is an impurity or contaminant in and/or a matrix.

Preferably said matrix is soil, clay or the like.

Preferably said organo-halogen compound is typified by, for example, DDT (or the related DDE, DDD), dieldrin, PCBs, etc.

Preferably said ball mill has balls of less than 30 mm diameter. Preferably the balls of the ball mill are of about 20 mm diameter. Preferably the ball mill is operated with sufficient energy so as to raise the mill mix temperature to at least 70 °C but to maintain the mill mix temperature below temperatures which will lead to excessive vaporisation of the organo-halogen compound being handled.

Preferably where the organo-halogen compound is DDT the operating temperature of the ball mill is in the range of from 70 to 140 °C (most preferably 70 to 110°C), [ie; the upper threshold being substantially below the vaporisation point of DDT in most of its forms which is at about 146 °C].

Preferably where the organo-halogen compound is dieldrin the ball mill is operated to a temperature range of from about 70 to 140° C (most preferably 70 ° to 110°C) which again is well below the vaporisation temperature which in respect of dieldrin in about 150 °C. in some forms of the present invention where a ball mill of sufficient energy is utilised urea may be used alone or in conjunction with a suitable acid.

In other forms a suitable iron sand or steel makers slag may be used alone or in conjunction with a suitable acid or urea. In preferred forms of the present invention both (I) a suitable iron sand and/or steel makers slag and (II) urea is utilised (optionally with (Hi) acetic acid or vinegar) and preferably also the ball mill is one with ferrous balls and/or a ferrous ball confinement chamber.

In still a further aspect the present invention consists in a method of reducing the DDT and/or dieldrin content of a contaminated matrix which comprises subjecting particles of such contaminated matrix to ball milling in the presence of urea at sufficient energy as to impart to the reaction mix a temperature of at least 70°C but below 146°C.

Preferably the reaction mix with such contaminated particles (percentages in respect to the amount of the contaminated matrix) comprises urea - 5 to 15% (preferably about 10% by weight) iron sand - 0 to 15% (preferably 5 to 10% by weight) acetic acid - 0 to 5% (preferably about 2% by weight).

Another procedure that takes advantage of low cost procedures is one where the reaction mix is as follows

- steel makers slag 1 to 15 % by w/w of contaminated material, - urea 1 to 15% by w/w of contaminated material, and

- (optionally and particularly if DDE is a contaminant) white vinegar (as a source of acetic acid) about 1% by w/w. The percentages take advantage of the iron values and titanium values of steel makers slag as is readily available in New Zealand to provide in conjunction with readily available urea and white vinegar an economic expendables input for such a ball milling procedure.

Preferably said contaminated particles are those of soil and/or clay and/or crushed rock in a substantially dry form.

Preferably the balls of said ball mill are less than 30mm in diameter and preferably are about 20mm or less.

Preferably the ball mill is one with ferrous balls and/or a ferrous ball confinement chamber. In still a further aspect the present invention consists in a method of decreasing the organo-halogen compound contamination of a media which involves a use of a method as aforesaid sufficient to reduce the level to one that is desired.

In a further aspect the present invention consists in a method of decontaminating an organo-halogen contaminated media (eg; soil) which comprises or includes milling the media (optionally in the presence of a suitable acid) with one or both of

(a) urea, and

(b) iron sand or any other metal values source (eg; steel makers slag). Preferably said milling is followed by a subsequent milling of the output of the first milling and such second milling is with the addition of one or both of i) urea, and ii) iron sand or any other metal values source (eg; steel makers slag).

There may be additional milling procedures.

In one form of the invention the initial milling is in the presence of acetic acid and/or iron sand. Urea may be present irrespective of whether or not acetic acid and/or iron sand is present.

Preferably the subsequent or a subsequent milling step involves the output of an earlier milling procedure and the addition of urea and/or iron sand.

Preferably said milling is in a ball mill and preferably said ball mill includes balls with an elementary iron content. Preferably at least one and preferably several, if not all, of the milling procedures are performed at an elevated temperature.

Preferably said elevated temperature is above 70 °C.

Preferably the elevated temperature is within a range as previously set forth. In some forms of the present invention the milling can be performed in a closed environment thereby to restrict (eg; by pressurisation, for example, in a pressure vessel) the loss of freed ammonia from the milling procedure.

In still a further aspect the present invention consists in a method of media decontamination which involves a procedure substantially as herein described with reference to any of the accompanying drawings and/or using any of the methods herein described.

In still a further aspect the present invention consists in a method of decontaminating a media (eg; soil and/or clay) which involves the performance of methods in accordance with the present invention at or adjacent the site of contamination utilising a ball mill positioned for the purpose.

Preferably said ball mill is apparatus as described in our patent application filed simultaneously herewith.

In still a further aspect the present invention consists in a method of soil or clay decontamination which comprises or includes subjecting at least the lower particulate sized fraction of the soil or clay to ball milling so as to perform a process as previously described.

Preferably said soil or clay has had larger particles removed therefrom or crushed.

In some preferred forms of the present invention a larger particle size fraction is separated from a finer particle fraction with the larger particle size fraction being subjected to optional exterior washing prior and/or to optional crushing and/or optional re-inclusion thereof with the finer particle size fraction before or after (preferably after) the subjection of the finer particle size fraction to the ball milling.

Preferably only once the larger particle size fraction is subjected to crushing are they subjected to the ball milling.

Preferably the smaller particle size fraction includes sizes generally less than 10 mm. Preferably the ball milling is for such duration as will reduce the less than 10 mm particle sizes to about 0.4 microns.

In still a further aspect the present invention consists in a method of decontaminating earth (whether one or more of top soil, clay, rock or the like) which comprises subjecting in a reasonably or substantially dry form the more contaminated smaller particulate fraction of he earth to a ball milling procedure which has the effect of reducing the DDT and/or dieldrin contamination thereof, such ball milling being for such duration at a temperature of at least 70 °C but below the boiling point of any part of the DDT and any dieldrin.

Preferably any one or more of the reactants previously described for inclusion in a reaction mix in such a ball mill is included. As used herein reference to the word "suitable" is such as will enable the desired outcome, namely, a reduction in the level of the organo-halogen compound in its original form. For example, a suitable acid is acetic acid (whether as white vinegar or otherwise) which (substantially as hereinafter described with reference to the examples) may be used in a first stage with, for example, urea and/or iron sand.

Preferably said "metal source" is a metal complex, ie; of several metals and/or at least one metal in one or more oxidation states (eg; a titanoferromagnitite), whether zero and/or otherwise.

Reference herein to "iron sand" includes any appropriate iron sand for the procedure. All such iron sands are preferably titanoferromagnetite sands. One such sand is that of, for example, BHP New Zealand Steel Limited having a content substantially as set out in Table 1 (being an analytical report of two samples).

As used herein DDT may also include the related DDD (ie DDT minus CI) and/or the reatled DDE (ie DDT minus HC1)

TABLE 1:

The Fe values are present in other than the zero oxidation state.

Reference hereto to "steel makers slag" includes any suitable slag with iron or titanium values but preferably is a slag with both iron and titanium values such as that of BHP New Zealand Steel Limited.

The slag such as that set out in Table 2 is preferably post-crushing, and magnestic extraction of any zero oxidation state values initially present prior to oxidation thereof.

Table 2 is an example of BHP New Zealand Steel Gap 10 slag.

TABLE 2:

The Fe values are present as oxides or other than zero oxidation state values.

Preferably reference to "elevated temperature(s)" is to temperature(s) below that at which the organo-halogen evaporates. By way of example, preferably in the range 70 °C to 140°C.

In still a further aspect the present invention consists in a method of decontaminating a media which involves a process in accordance with the present invention as previously defined and one or more of the procedures hereinafter described with or without reference to any of the accompanying drawings.

In still a further aspect the present invention consists in a method of decontaminating soil contaminated with an organo-halogen compound (for example, DDT, DDE, DDD, Dieldrin, PCBs, dioxins, halogenated furans and lindane) which involves the step of

(optionally) separating large materials from the soil, and (optionally) washing such larger materials), presenting the soil (optionally free of larger materials) [preferably in a dry condition] into apparatus capable of "milling" the soil plus reagent(s) together sufficient to achieve desired reactions [eg; one or more vibratory and/or ball mills] during which use of a procedure or procedures as herein described ensures there is a reduction in the organo-halogen compound, content and thereafter preparing the material for deposition (preferably at the site from which it has been removed (optionally) after reintroduction thereto of any larger particulate material that may have been removed therefrom).

Preferably said material after the ball mill(s) is subjected to a process which tends to ensure a better agglomeration property thereof.

Preferably such process involves the addition of a suitable polymer or other material (eg; urea itself or lime).

Preferably one or a series of ball mills are utilised and preferably the reactants are (I) iron sand and/or steel makers slag and (II) urea with optionally (III) a suitable acid as well (preferably acetic acid), preferably the staging being substantially as herein described.

Preferably the reaction conditions in each ball mill is such that the mechanical agitation is at a temperature of 70 °C or above.

Preferably the system or plant is such as will perform a procedure substantially as hereinafter described with reference to Figure 1 and/or Figure 2. In still a further aspect the invention consists in degrading a persistent/toxic organo- halogen into safer form(s) which includes, at elevated temperatures (eg; as in, say, a ball mill above, say, 70 °C), vigorously mixing the organo-halogen with (in any order if sequential, or simultaneously) reagents:

(I) urea or iron sand or steel makers slag, (II) (A) if (I) is urea, iron sand and/or a source of a reactive metal or

(B) if (I) is iron sand, a suitable amide and/or urea, or

(C) if (I) is steel makers slag, a suitable amide and/or urea, and (III) optionally an acid (eg; acetic acid).

Optionally other reagents may be included. The present invention also consists in reaction products or detoxification media and/or soil resulting from a process or procedure of the present invention.

A preferred form of the present invention will now be described with reference to the accompanying drawings in which Figure 1 is a simplistic two stage milling procedure in accordance with the present invention capable of reducing the level of, for example, DDT (and/or the related DDE and

DDD) and/or Dieldrin in soils although not restricted to such organo-halogens as such process is applicable with different effectiveness to others such as PCBs, dioxins, halogenated furans and lindane, and

Figure 2 is one preferred plant/flow diagram,

Figure 3 is a preferred flow diagram in accordance with the present invention showing by same reference numerals as used in Figure 2 some of the components in common between the slightly different processes of Figures 2 and 3, Figure 4 is a flow diagram showing how preferably two larger particle streams are utilised and preferably each is crashed to the extent necessary to ensure proper stabilisation of the small particle sizes provided as the decontaminated outflow from the dehalogenation plant, the fines (where the bulk of halo-organic contamination lies in soil and/or clays) preferably alone being dehalogenated, and Figure 5 is a simplified side elevation view of a preferred transportable unit capable of being utilised to initiate a treatment site in conjunction preferably with other transportable componentry.

In a preferred form the procedure is as follows:

Stage I: Ball Milling of the soil (wet or dry) [with/without acetic acid (or any other suitable acid)] with urea preferably and/or iron sand (or any other metal source).

Stage II: Ball Milling of the Stage 1 output with additional urea (optionally with iron sand and/or optionally with acetic acid (or other suitable acid).

Features:

The use of a ball mill to drive the reaction

Preferably multiple batches

Temperature for the step involving urea (preferably should be >70°C) can vary the number of batches process can instead be continuous or in batches can vary the order of reagent addition (eg; adding urea before or after iron sand or steel makers slag addition). can consider pretreatment of lime (calcium oxide or calcium sulphate) to dry (at least in part) soil mixture. Preferred Starting Point:

Soil (or any other solid or liquid form) contaminated with any halo-organic substance. Our tests to date have been performed on soil contaminated with DDT, DDE and Dieldrin.

Preferred End-Point:

A significant reduction in halo-organic compounds, such that soil (or any other solid or liquid form) that was contaminated preferably meets regulatory guidelines for residential or industrial use, or guidelines for disposal in a landfill (whether with reblending with removed larger material (ground to finer sizes or not) or not). Figure 1 shows several preferred variants.

In a preferred form of the present invention the flow diagram is as shown in Figure 2. First there is an elimination of contaminated earth (1). That contaminated soil is preferably then passed through a rotary screen 2 with larger materials, eg; stones, being passed to a washer 3 and then being stockpiled at 4. Material (eg; soil or clay) is subjected to a primary separation (eg; using a screen 2) to provide two streams. The fine material stream is preferably further streamed in a dry trommel 5 to provide a second larger particle stream. The second finer particle stream is optionally dried at 9 prior to entry into a hopper 11.

The first larger particle stream from screen 2 is washed at 3 and stockpiled at 4. Thereafter as required it may be reduced in particle size in a "crusher" 20. The second larger particle stream in vibrating screen 6 removes clay and fines go to dryer 9 optionally via a drier

(eg; solar rotary dryer 8). Larger particles from scrubber 7 go into crasher 20 and, only if of lower contamination, directly to mixer 18. If however of higher contamination such out feed should go to dryer 9 and or hopper 11.

The dry materials of small particle size (preferably 0 to 5 mm in particle size) is passed into an optional dryer 9 and thereafter enters into an auger 10 via a hopper 11. It is possible therefore for the material from 9 to be passed directly only into the first ball mill 12 and thereafter have other reagent or reagents from either or both hoppers 13 and 14 fed via the worm feed 10 to premix with the out feed from either the first ball mill 12 or the second ball mill 15. A third ball mill 16 is provided to which, if desired, a recycle feed from the output can be provided.

While reference is made to ball mills, one or more of them may be substituted with other milling form of apparatus. Also the same ball mill can be used in a staged version of the overall process. Means to feed a polymer or even urea and/or lime 17 is preferably provided such that the output from the ball mill 16 can be agglomerated at 18 and then stockpiled at 19 with an option of some recycle back into ball mill or reactor 3. The output otherwise from the stockpiles 19 can go to site reconstruction, ie; for example, back to the site of the soil elimination 1.

The stockpile material 4, if desired, can be passed along with heavier material from scrubber 7 into a crasher or breaker 20 and from thence into the output from ball mill 16 to further dilute the effect of any remaining unreacted and unmodified organo-halogen material in the output from the third stage reaction. Figure 3 shows an alternative procedure to that of Figure 1. Here it can be seen that the excavation at 1 visually recognises clay layers and treats them to drying in a solar drying room 8 whereupon they are fed as stream 28 along with a fines stream 27 from the jaw crasher 20 into the reactor 21, they are preferably pre-blended for that purpose with the fines output of the rotary dryer 9. It can be seen in Figure 3 and this is better described in the flow diagram of Figure 4 that there are three particle separations quite apart from the visual identification of clay and in this respect there is the fine stream of 0 to 10 mm that is treated to the dry trommel and rotary dryer whilst the 11 to 20 mm particles are those extracted at the secondary screen 6 whilst the larger particle stream of ≤20 mm is that isolated from the primary screen 2. It can be seen to that the output 39 from the jaw crusher which is preferably of particles greater than those from the outlet 24 of the reactor 1 are blended so as to stabilise the soil against matting when wet. In this respect a zone 40 provides such blending which henceforth we shall refer as Geotech™ blending. This blends with larger particle sizes the micron sized particles from the reactor. As can be seen the reactor has upper and lower cylinders 22 and 23 through which the reaction mix of fines as well as the reagents referred to herein moves with the dwell time in the reactor being controlled by the ratio of infeed at 25 against out take at 24.

The unit designated generally as 21 is preferably as described in the specifications filed simultaneously herewith but preferably utilises a Palla 65U ball mill of KHD Humboldt Wedag AG of Germany having ball sizes below 30 mm in diameter (preferably from 15 to 25 mm diameter) (eg; 20 mm in diameter which are of steel or iron within the iron reactant reactor cylinders). The ball mill is supported on a mobile chassis 36 with upstanding pedestals 27 on which the vibrating mass of inlet 25, cylinder 25, cylinder 23 and out take 24 can vibrate violently under the rotation of the drive shaft 32 driven eccentric or eccentrics. Preferably the ball mill is straddled by banks of the pedestals 27 and the synthetic or natural rubber pads 38 allow the degree of movement required.

Preferably the unit 36 with a static mass sufficient to counter weight the vibrating masses of the ball mill assembly is driven by an engine 30 (preferably a GM Detroitt Diesel 8N71 producing 600 BHP and a maximum torque of 3500 ΝM) such that via a torque converter or more preferably an overcentre clutch (twin disc) 31 the shaft 32 can be rotated from rest. Preferably to allow braking of the ball mill when the clutch is engaged a brake 33 is provided. It has been found that with the apparatus of the present invention a direct drive of 1 : 1 is possible from such a engine or its equivalent and such a ball mill or its equivalent, (ie; no reduction needed) and it is possible once the maximum torque requirement at about 150 rpm has been encountered to operate the shaft and thus the engine and ball mill at about 1200 rpm.

Preferably the engine 30 has a minimum power output of 400 BHP with no upper limit.

Preferably however for economy of use the engine is a diesel capable of producing 600 BHP and greater than 3396 ΝM.

Also mounted on the chassis or frame unit 36, 37 et al. is an extractor fan 34 for operating air filters 35. The addition of this additional plant all within the ambit of a 40ft ISO container size increases the counterweight mass for the vibrating unit without providing any unacceptable increase in size. In the following examples, except where otherwise stated, all percentages are on a weight/weight basis.

Example 1:

Soil (7 kg) contaminated with DDT (390 mg/kg dry weight) and dieldrin (71.4 mg/kg dry weight) was mixed with acetic acid (250 g, 99.7% purity), water (380 g) and iron sand

(1.40 kg). The 7 kg soil sample was undried and had a moisture content of 9.3% prior to the addition of any reagents or additional water. This mixture was then placed in a vibratory ball mill and milled for 30 minutes. The mill was then discharged, and urea (1.05 kg) and iron sand (700 g) were mixed into the soil. The mill was reloaded, and the mixture milled for a further 30 minutes. The mill temperature was above 70°C for the entire procedure.

GC-ECD analysis showed a 99% reduction in DDT levels, and a 99.1% reduction in dieldrin levels. No other halo-organic substances were detected.

Example 2: Soil (7 kg) contaminated with DDT (390 mg/kg dry weight) and dieldrin (71.4 mg/kg dry weight) was mixed with vinegar (630 g) and cast iron filings (1.40 kg). The soil was undried and had a moisture content of 9.3% prior to the addition of vinegar. This mixture was placed in a vibratory ball mill and milled for 30 minutes. The mill was then discharged, and urea (1.05 kg) and iron sand (700 g) were mixed into the soil. The mill was reloaded, and the mixture was ground for a further 30 minutes. The mill was discharged again, an additional batch of urea (1.05 kg) and cast iron (700 g) was mixed into the soil, and the mixture was milled for a further 30 minutes. The mill temperature was above 90°C for the entire process.

GC-ECD analysis showed a 98.4% reduction in DDT levels, and a 99.7% reduction in dieldrin levels. No other halo-organic substances were detected.

Example 3:

Soil (7 kg) contaminated with DDT (390 mg/kg dry weight) and dieldrin (71.4 mg/kg dry weight) was mixed with vinegar (630 g) and cast iron filings (1.40 kg). The soil was undried and had a moisture content of 9.3% prior to the addition of vinegar. This mixture was placed in a vibratory ball mill and milled for 20 minutes. The mill was then discharged, and urea (700 g) and iron sand (700 g) were mixed into the soil. The mill was reloaded, and the mixture was ground for a further 20 minutes. The mill was discharged again, an additional batch of urea (700 g) and cast iron (700 g) was mixed into the soil, and the mixture was milled for a further 20 minutes. The mill temperature was above 85 °C for the entire process.

GC-ECD analysis showed a 97.9% reduction in DDT levels, and a 99.0% reduction in dieldrin levels. No other halo-organic substances were detected.

Example 4:

Soil (7 kg) contaminated with DDT (390 mg/kg dry weight) and dieldrin (71.4 mg/kg dry weight) was mixed with iron sand (1.40 kg), calcium sulphate (700g) and urea (700g). The soil was undried and had a moisture content of 9.3%. This mixture was placed in a vibratory ball mill and milled for 30 minutes. The mill was then discharged, and urea (350 g) and iron sand (350 g) were mixed into the soil. The mill was reloaded, and the mixture was ground for 15 minutes. The mill was then discharged again, and an additional batch of urea (350 g) and iron sand (350 g) was mixed into the soil. This mixture was milled for 15 minutes. The mill temperature was above 70 °C for the entire process. .

15

GC-ECD analysis showed a 96.9% reduction in DDT levels, and a 98% reduction in dieldrin levels. No other halo-organic substances were detected.

Example 5: Soil (7 kg) contaminated with DDT (390 mg kg dry weight) and dieldrin (71.4 mg/kg dry weight) was mixed with iron sand (1.40 kg) and urea (700g). The soil was oven-dried at 60^°C prior to use. This mixture was fed through an open vibratory ball mill. The residence time in the mill was 6 minutes. Additional urea (350 g) and iron sand (700 g) was mixed into the soil, and the mixture was fed through an open mill. The mill took 9 minutes to discharge. A final batch of urea (350 g) and iron sand (700 g) was mixed into the soil, and the soil was once again fed through an open vibratory bore mill. The time taken for total mill discharge was 14 minutes. This mixture was milled for 15 minutes. The mill temperature was above 70 °C for the entire process.

GC-ECD analysis showed a 95.1% reduction in DDT levels, and a 90.9% reduction in dieldrin levels. No other halo-organic substances were detected.

Example 6:

Soil (6.62 kg, oven-dried and pre-milled) contaminated with DDT (720 mg/kg dry weight) and dieldrin (64 mg/kg dry weight) was mixed with iron sand (1.24 kg) and urea (1.24 kg). This mixture was placed in a vibratory ball mill and milled for 30 minutes. The top of the mill was then opened, and urea (662 g) was poured in on top of the soil. The mixture was then milled for a further 30 minutes.

GC-ECD analysis showed a >99% reduction in DDT levels, and a >97% reduction in dieldrin levels. No other halo-organic substances were detected.

Example 7A and 7B:

Soil (3.2 kg, oven-dried) contaminated with DDT (868 mg/kg) and dieldrin (64 mg/kg) was mixed with magnesium filings (160 g) and milled for 10 minutes. Butylamine (160 g) was then added and the mixture was milled for a further 10 minutes. GC-ECD analysis showed this trial (Example 7A) a 65.7% reduction in DDT levels, and a 46.9% reduction in dieldrin levels. It should be noted that DDT isomers were replaced by DDE, i.e. a significant increase in DDE isomers was observed. It appears that this process as disclosed in PCT/DE98/02787 is not effective for treating DDE isomers. This trial has a shorter time in the mill and lower reagent percentages than the more successful. A repeat (Example 7B) with the same conditions save using urea instead of butylamine resulted in 93.5% DDT reduction and 68.8% dieldrin reduction.

Example 8

To test mechanical/chemical effects on changing ball diameter from 30mm to 20mm in a steel ball mill.

Sample:

15kg uncontaminated soil dried.

Spiked with 150g DDT concentrate 20%, and 150g dieldrin concentrate 4% (both liquid), hand mixed, then mixed for 30 minutes in concrete mixer.

Sample A taken.

Mill warmed and cleaned with 7kg DDT/Dieldrin spiked soil (as in Sample A) and

10% urea.

Spiked with 5% urea and 5% iron sand

Mill run for 20 minutes and then discharged for 15 minutes.

Sample B taken.

Mill warmed and cleaned with 7kg DDT/Dieldrin spiked soil (as in Sample A) and

10% urea.

Spiked with 5% urea and 5% iron sand.

Mill run for 20 minutes and then discharged for 15 minutes.

Sample C taken.

TABLE 3 - Example 8 Results:

Example 9

Rod Milling Verses Ball Milling:

Contaminated Mapua soil (7kg), iron sand (10%) and urea (5%) were mixed and milled for 10 minutes (sample (I)).

An additional 5% urea was mixed in, and the mixture milled with ferrous rods (not balls) for an additional 10 minutes (sample (II)).

The rods were replaced with ferrous balls of substantially similar mass, and another 5% of urea was added to sample (II), and it was milled for a further 20 minutes. Sample (III) was taken at the beginning of the discharge, sample (IN) was taken at the end of the discharge.

At a later date, a further 5% of urea was added to sample (IN), and it was milled for a further 30 minutes (sample (N)).

At a still later date, a further 5% portion of urea was added to sample (N), and it was milled for a further 60 minutes (sample (VI)).

All milling were as a similar energy input.

TABLE 4 - Example 9 Results:

Dehalogenation does not occur as effectively when balls inside the mill were substituted with rods.

Example 10

Sydney clay (6.13 kg), iron sand (613g, 10%) and urea (307g, 5%) were mixed well and milled for 10 minutes (sample (i)). Another 5% of urea was mixed in, and the mixture milled for a further 10 minutes (sample (ii)).

NB: the mill was filled with ferrous rods, not ferrous balls for samples (i) and (ii).

The rods were replaced with ferrous balls, and the mixture was milled for a further 20 minutes (sample (iii)).

5% iron sand and 5% urea (307 g of each) was then mixed in, and the mixture milled for 10 minutes (sample (iv)).

Acetic acid (200 g) was then added, and the mixture milled for 10 minutes (sample

(v)).

Another 5% urea was added to the soil, and this mixture was milled for a further 20 minutes (sample (vi)).

TABLE 5 - Example 10 Results

Clearly ball milling is a preference over rods even for contaminated clays.

Example 11

Sydney clay (3 kg) (as used in Example 10) had iron sand (10%) and acetic acid (3%) added to it. The mixture was run through ball mill, and samples were taken after 40 min (Sample (A)).

At a later date, another 10% urea was added to the mixture, and it was milled 2 x 30 minutes (sample (B)). • I

19

TABLE 6 - Example 11 Results

Example 12

Mapua soil with a mean contamination content in a less than 5 mm screened fraction of 71.9 mg/kg of dry weight Dieldrin and of 412 mg/kg of dry weight total of DDT isomers was then subjected to a milling procedure.

Soil Preparation

Contaminated soil as excavated was spread out on a tarpaulin and mixed well. Soil was then sieved through a 5mm sieve. The < 5mm fraction was collected and dried overnight in an oven kept at 50 °C prior to use in the milling trials. The > 5mm fraction was used in soil washing trials. Approximately 43% of stockpile was < 5mm, and approximately 57% was > 5mm.

Initial Concentrations of DDT and dieldrin in < 5mm Soil Fraction:

Portions of the <5mm fraction were oven-dried at 50 °C overnight, ground in the mill and analysed for DDT and dieldrin. Results are presented in Table 7.

TABLE 7 - Initial DDT (which may included the related DDE, DDD) and Dieldrin

Concentrations

Mechanochemical Dehalogenation Process (MCD) Trial carried out in triplicate Procedure:

Soil (4kg of the oven-dried <5mm fraction) was mixed with iron sand (200g, 5%) and acetic acid (2%). This mixture was introduced into the ball mill and milled for 30 minutes. The mill was the discharged, and a soil sample (150g) was taken. The milled soil was then mixed well with urea (400g, 10%) and iron sand (200g, 5%). This mixture was milled for a further 30 minutes. The mill was then discharged, and tlie soil was re-introduced into the mill (no extra reagent addition), and milled for another 30 minutes. A sample (150g) was taken for analysis.

The above trial was carried out in triplicate (Runs A, B and C). Results are shown in Table 8. TABLE 8 - Results from Trial Carried Out in Triplicate (Runs A, B & C):

TABLE 9 - Statistical Analysis of Treated Soil (Triplicate Trials)

From these results it can be seen that an initial concentration of 71.9 (+/- 2.2) ppm dieldrin in our source has been reduced to 0.5 (+/- 0.2) ppm. Likewise, an initial concentration 412 (+/- 35) ppm DDT in our source has been reduced to (4.8 +/- 1.1) ppm. It should be noted that these results are for the highly contaminated < 5mm fraction. Recombination of this soils with the washed > 5mm fraction will further decrease both DDT and dieldrin concentrations.

Soil Washing Trial

Two runs with the same soil source were carried out in order the determine the effectiveness of washing the > 5mm fraction from our source. Soil was washed in a cement mixer that had 5mm holes around the edge. Results are presented in Table 10.

TABLE 10 - Results from Soil Washing Trials of Larger than 5 mm Fraction.

Application of The Process Range of Contaminants and Waste Material Expected.

Our pilot plant trials conclude that initial pesticide reductions, using the process of concentrations where the variations of DDT from 850 mg/kg to 320 mg/kg has little impact in the first stage of the process. This means the process has little problem in quickly achieving reductions of DDT down to 50 mg/kg.

In respect of dieldrin, the same can be said, where initial concentrations have varied from 80 mg/kg to 70 mg/kg. First stage results generally are down to the region of 10 mg/kg.

Example 13:

We have tested the MCD Process on clay from a different site, and found that it works effectively on clay as well as on soil. We expect the MCD Process to dehalogenate all halogenated contaminants present. This includes PCBs. Substances such as heavy metals or sulphur should not affect the MCD Process, however, it should be noted that the MCD Process does not eliminate heavy metals, and if these are present above acceptable levels, those portions of soil may have to be landfϊlled.

Example 14:

Trial: To test process with each of SR3-BHP New Zealand Slag and Gap 10 slag of BHP New Zealand Steel Limited.

- The general chemical composition of SR3-BHP New Zealand Slag is more akin to "pig iron"

- The general chemical composition of the BHP New Zealand Gap 10 slag is as follows:

SiO₂ - 11.32%

TiO₂ - 31.34%

MgO - 12.76%

CaO - 15.98%

Total Fe values - 8.45%

A1A - 16.88%

V₂O₃ - 0.28%

MnO - 0.88%

S - 0.1 8%

15kg of dried sand slag (screened to particle size less than 7 mm) was mixed with lOOg DDT (12.5% concentrate) pellets and 75g dieldrin (4% concentrate) liquid. The product was mixed for 10 minutes in the mixer. The Control Sample was extracted.

Run l: 5kg of material identical to the control sample was extracted from the mixer,

The material was mixed with 10% of the SR3 slag, 5% of unfiltered white vinegar

(10%) concentrate) and 5% urea.

The mill was operated for 20 minutes.

The Run 1 sample was extracted.

Run 2:

5kg of the material identical to the control sample was extracted from the mixer. The material was mixed with 10% unscreened slag sand, 5% unfiltered white vinegar (10% concentrate) and 5% urea. The mill was operated for 20 minutes. The Run 2 sample was extracted.

Run 3:

5kg of material identical to the control sample was extracted from the mixer.

- The material was mixed with 10% of Gap 10 slag (ie, screened to particle size less than 10 mm), unfiltered white vinegar (10% concentrate) and 5% urea.

- The mill was operated for 20 minutes.

- Run 3 sample was extracted.

TABLE 11 - Results:

Example 15:

Trial: To test the Process in Respect to PCBs. - 5kg of dried Gap 7 BHP New Zealand slag (screened to particle size less than 7mm) to simulate soil was mixed with 32 grams of liquid PCB. - Control Sample extracted. Material identical to the Control Sample was mixed with 10% by weight of the Gap 10 sand (ie slag screened to particle size less than 10 mm), 5% of dry untreated vinegar (10% concentrate) and 5% urea. Run 1 sample extracted.

TABLE 12 - Results: (ppm)

Example 16:

Trial: To Check DDT/Dieldrin Reaction with Lower Ratios of Some Reagents

- 5kg of the same dried slag sand (screened to particle size less than 7 mm) to simulate slag was mixed with 33g of DDT and 26g dieldrin (similar ratios as Example 14).

- Control sample extracted.

- Material with content as in the control was mixed with 10% by weight of GAP 10 slag but 2.5%) white vinegar (10% concentrate) and 2.5% urea.

- The mill was run for 20 minutes.

- Run 1 sample extracted.

TABLE 13 - Results:

Example 17:

A Full Scale Trial:

- 2 cubic metres of aggregate (screened to particle size less than 7mm), solar dried and having a specific gravity of 1558 kg/m³ was mixed with 10% by weight BHP New Zealand steelmakers slag (screened to less than 10mm and having had any iron present removed magnetically) and 10% by weight urea.

- The material spiked with 4 kg of 50% concentrate DDT in powder form and thoroughly mixed.

- It was then further mixed with 7.5 kg of 4% concentrate dieldrin pellets. Mixing was done using a mini-excavator for a period of three hours.

The mixed product was sampled to provide the spiked sample.

Product was then loaded into the reactor and the discharge was collected.

TABLE 14 - Results:

Proposed Methodology in Practice

See enclosed Figures 1 to 5 hereof and our patent applications filed simultaneously herewith. Excavation of Contaminated Material

Material will be excavated from agreed contamination zones, to designated depths by a tracked excavator, having a wide bucket, with a sharp cutting edge.

Visual Product Selection

(i) Majority of Excavated Product (Excluding Clay Seams) Post excavation transport, product is fed on to a primary screen where the oversize rock

(> 100mm) will be stockpiled. Subject to further analysis (this has not been done because the representative sample was screened to < 50mm), if contamination levels require remediation, this sized product can be either washed, or crushed and run through the dehalogenation plant. If this product meets a satisfactory standard, subject to client specifications, it can be crashed and used as fill or placed as base course. The process diagram incorporates a washing system, and if needed a simple trommel is used. Product screened to < 50mm will is placed in a dry trommel, and screened to < 5mm, prior to loading into the MCD Plant.

Product > 5mm is washed in a wet trommel, where the extracted sediment is rotary dried and joins the < 5mm particle sizing. The > 5mm washed product, is crushed to client preference, sizing and also replaced on site as base fill and/or be part of the end product homogenized mix.

(ii) Clay Identifying specific clay seams, during excavation is important. Physical clay seam separation during excavation for separate drying reduces processing costs. Pre-drying would be of a passive type, in a dedicated fully enclosed shed, constructed on site, similar to a commercial vegetable growers hothouse. An air extraction/dust collection system will be installed.

(iii) Quantities of Additives-.

Additives, used in the pilot plant, which might be introduced in a full scale plant are

• Additive A - Iron Sand or Steel makers Slag (10% - by product dry weight) • Additive B - Acetic Acid (2% - by product dry weight) [eg; as white vinegar].

• Additive C - Urea (10% - by product dry weight)

Claims

1. A method of reducing the levels of an organo-halogen compound which involves the milling of the compound in the presence of one or more of:

(I) urea with a suitable metal source,

(II) a suitable iron sand with a suitable amide,

(III) a suitable iron sand with a suitable acid,

(IV) a suitable iron sand with a suitable hydrogen donor, (V) a suitable iron sand with a suitable acid and a suitable amide,

(VI) a suitable iron sand with a suitable acid and a suitable hydrogen donor,

(Nil) urea,

(NIII) urea with a suitable acid,

(IX) urea with a suitable acid and a suitable metal source, (X) steel makers slag,

(XI) steel makers slag with a suitable amide,

(XII) steel makers slag with a suitable acid,

(XIII) steel makers slag with a suitable acid and a suitable amide,

(XIV) steel makers slag and urea, and (XN) steel makers slag, urea and a suitable acid.

2. A method as claimed in claim 1 wherein the organo-halogen compound is within contaminated media.

3. A method as claimed in claim 1 or 2 wherein the milling is single or mutiple, simultaneous or sequential.

4. A method of reducing the level of at least one organo-halogen compound in and/or on a matrix which comprises or involves milling the matrix with at least one organo-halogen compound in a ball mill with one or more of a) urea, b) an iron sand, c) steel makers slag, and/or d) a suitable acid.

5. A method as claimed in claim 4 wherein at least urea is employed.

6. A method as claimed in claim 5 wherein the urea is used with an iron sand or with steel makers slag.

7. A method as claimed in any one of claims 4 to 6 wherein the energising of the ball mill is such that a temperature of at least substantially 70 °C is generated in the ball mill mix.

8. A method as claimed in claim 7 wherein the ball mill is of a kind with ferrous balls and/or a ferrous ball confinement chamber.

9. A method as claimed in any one of claims 4 to 8 wherein the organo-halogen compound is an impurity or contaminant in, and/or a matrix.

10. A method as claimed in claim 9 wherein the matrix is soil, clay or the like.

11. A method as claimed in claim 10 wherein the organo-halogen compound is typified by, for example, DDT (or the related DDE, DDD), dieldrin, PCBs, etc.

12. A method as claimed in claim 11 wherein the ball mill has balls of less than 30 mm diameter.

13. A method as claimed in claim 12 wherein the balls of the ball mill are of substantially 20 mm diameter.

14. A method as claimed in any one of claims 4 to 13 wherein the ball mill is operated with energy in a range capable of raising the mill mix temperature to at least 70 ° C, but also of maintaining the mill mix temperature below temperatures which will lead to excessive vaporisation of the organo-halogen compound being handled.

15. A method as claimed in claim 14 wherein the organo-halogen compound is substantially DDT and the operating temperature of the ball mill is in the range of from 70 to 140° C [ie; the upper threshold being substantially below the vaporisation point of DDT in most of its forms which is at about 146°C],

16. A method as claimed in claim 15 wherein the temperature range is 70 to 110 °C.

17. A method as claimed in claim 14 wherein the organo-halogen compound is substantially dieldrin and the ball mill is operated to a temperature range of from about 70 to l40°C which again is well below the vaporisation temperature which in respect of dieldrin in about 150°C.

18. A method as claimed in claim 17 wherein the temperature range is 70 to 110°C.

19. A method as claimed in any one of claims 4 to 18 wherein when a ball mill of sufficient energy to enable reduction of the levels of the organo-halogen compound is utilised, urea may be used alone or in conjunction with a suitable acid.

20. A method as claimed in any one of claims 4 to 18 wherein a suitable iron sand or steel makers slag may be used alone or in conjunction with a suitable acid or urea.

21. A method as claimed in claim 20 wherein both

(I) a suitable iron sand and/or steel makers slag and

(II) urea are employed.

22. A method as claimed in claim 21 wherein (III) acetic acid or vinegar is further employed.

23. A method of reducing the DDT and/or dieldrin content of a contaminated matrix which comprises or includes subjecting particles of the contaminated matrix to ball milling in the presence of urea at sufficient energy as to impart to the reaction mix a temperature of at least 70°C but below 146°C.

24. A method as claimed in claim 23 wherein the reaction mix with such contaminated particles comprises or includes: urea - 5 to 15% iron sand - 0 to 15% acetic acid - 0 to 5% (% in respect to the amount of the contaminated matrix).

25. A method as claimed in claim 24 wherein the reaction mix with such contaminated particles comprises or includes: urea - substantially 10% by weight iron sand -substantially 5 to 10% by weight acetic acid -substantially 2% by weight.

26. A method as claimed in claim 23 wherein the reaction mix with such contaminated particles (% in respect to the amount of the contaminated matrix) comprises or includes: steel makers slag - 1 to 15%, urea - 1 to 15% (by w/w of contaminated material).

27. A method as claimed in claim 26 wherein, particularly if DDE is a contaminant, white vinegar is further employed as a source of acetic acid, at substantially 1% by w/w.

28. A method as claimed in any one of claims 23 to 27 wherein the percentages substantially relate to the iron values and titanium values of steel makers slag as is readily available in New Zealand to provide in conjunction with readily available urea and white vinegar an economic expendables input for such a ball milling procedure.

29. A method as claimed in any one of claims 23 to 28 wherein the contaminated particles are those of soil and/or clay and/or crushed rock in a substantially dry form.

30. A method as claimed in claim 29 wherein the ball mill contains balls having a diameter substantially less than 30mm.

31. A method as claimed in claim 30 wherein the balls of the ball mill are substantially 20mm or less.

32. A method as claimed in claim 31 wherein the ball mill is one with ferrous balls and/or a ferrous ball confinement chamber.

33. A method of decreasing the organo-halogen compound contamination of a media which involves a use of a method as aforesaid sufficient to reduce the level to one that is desired or required by governmental or other standards.

34. A method of decontaminating an organo-halogen contaminated media (eg; soil) which comprises or includes milling the media with one or both of

(a) urea, and

(b) iron sand or any other metal values source (eg; steel makers slag).

35. A method as claimed in claim 34 wherein the milling is in the presence of a suitable acid.

36. A method as claimed in claim 34 or 35 wherein the milling is a first milling, and which is followed by a second milling of the output of the first milling wherein such second milling is with the addition of one or both of i) urea, and ii) iron sand or any other metal values source (eg; steel makers slag).

37. A method as claimed in claim 36 wherein there are further additional milling procedures or steps.

38. A method as claimed in 36 or 37 wherein the first milling is in the presence of acetic acid and/or iron sand.

39. A method as claimed in claim 38 wherein urea is additionally present.

40. A method as claimed in any one of claims 36 to 39 wherein the second milling, or any subsequent milling step involves the output of an earlier milling procedure and the addition of urea and/or iron sand.

41. A method as claimed in any one of claims 34 to 40 wherein the milling is in a ball mill.

42. A method as claimed in claim 41 wherein the ball mill includes balls with an elementary iron content.

43. A method as claimed in claim 42 wherein at least one and preferably several, if not all, of the milling procedures are performed at an elevated temperature.

44. A method as claimed in claim 43 wherein the elevated temperature is above 70 °C.

45. A method as claimed in claim 44 wherein the elevated temperature is above 70 °C but substantially below a temperature at which vaporisation of the organo-halogen contaminant(s) occurs.

46. A method as claimed in any one of claims 1 to 45 wherein the milling can be performed in a closed environment thereby to restrict the loss of freed ammonia from the milling procedure.

47. A method as claimed in claim 46 wherein the closed environment is further ensured by use of pressurisation, in a pressure vessel.

48. A method of media decontamination which involves a procedure substantially as herein described with reference to any of the accompanying drawings and/or using any of the methods herein described.

49. A method of decontaminating a media which involves the performance of methods in accordance with the present invention at or adjacent the site of contamination utilising a ball mill positioned for the purpose.

50. A method a claimed in claim 49 wherein the media is soil and/or clay.

51. A method as claimed in claim 50 wherein the ball mill is apparatus as described with reference at least to Figure 5.

52. A method of soil or clay decontamination which comprises or includes subjecting at least the lower particulate sized fraction of the soil or clay to ball milling so as to perform a process as previously described.

53. A method as claimed in claim 52 wherein the soil or clay was subject to a prior step of removal, or crashing of larger particles.

53. A method as claimed in claim 52 or 53 wherein a larger particle size fraction is separated from a finer particle fraction with the larger particle size fraction being subjected to optional exterior washing prior and/or to optional crushing and/or optional re-inclusion thereof with the finer particle size fraction before or after (preferably after) the subjection of the finer particle size fraction to the ball milling.

54. A method as claimed in claim 53 wherein only once the larger particle size fraction is subjected to crushing are they subjected to the ball milling.

55. A method as claimed in claim 54 wherein the smaller particle size fraction includes sizes generally less than 10 mm.

56. A method as claimed in claim 55 the ball milling is for such duration as will reduce the less than 10 mm particle sizes to about 0.4 microns.

57. A method of decontaminating earth (whether one or more of top soil, clay, rock or the like) which comprises subjecting in a reasonably or substantially dry form the more contaminated smaller particulate fraction of he earth to a ball milling procedure which has the effect of reducing the DDT and/or dieldrin contamination thereof, such ball milling being for such duration at a temperature of at least 70 °C but below the boiling point of any part of the DDT and any dieldrin.

58. A method as claimed in claim 57 wherein any one or more of the reactants previously described for inclusion in a reaction mix in such a ball mill is included.

59. A method of decontaminating a media which involves a process in accordance with the present invention as previously defined and one or more of the procedures hereinafter described with or without reference to any of the accompanying drawings.

60. In still a further aspect the present invention consists in a method of decontaminating soil contaminated with an organo-halogen compound (for example, DDT, DDE, DDD, Dieldrin, PCBs, dioxins, halogenated furans and lindane) which includes the steps of

A) presenting the soil into apparatus capable of "milling" the soil plus reagent(s) together sufficient to achieve desired reactions [eg; one or more vibratory and/or ball mills] during which use of a procedure or procedures as herein described ensures there is a reduction in the organo-halogen compound, content and

B) thereafter preparing the material for deposition.

61. A method as claimed in claim 60 wherein prior to A) and B) there is a preparation step which includes one of more of the steps of

-separating large materials from the soil, - washing such larger materials, and -drying the materials

62. A method as claimed in claim 60 or 61 wherein step B) occurs at the site from which the material has been removed.

63. A method as claimed in claim 60, 61 or 62 wherein step B) occurs after reintroduction thereto of any larger particulate material that may have been removed therefrom.

64. A method as claimed in claim 63 wherein said material after the ball mill(s) is subjected to a process which tends to ensure a better agglomeration property thereof.

65. A method as claimed in claim 64 wherein such process involves the addition of a suitable polymer or other material (eg; urea itself or lime).

66. A method as claimed in claim 65 wherein one or a series of ball mills are utilised.

67. A method as claimed in claim 66 wherein the reactants are (I) iron sand and/or steel makers slag and

(II) urea.

68. A method as claimed in claim 67 wherein there is further (III) a suitable acid

69. A method as claimed in claim 68 wherein the acid is acetic acid.

70. A method as claimed in claim 69 wherein the reaction conditions in each ball mill is such that the mechanical agitation is at a temperature of 70 °C or above.

71. A method as claimed in claim 70 wherein the system or plant is such as will perform a procedure substantially as hereinafter described with reference to Figure 1 and/or Figure 2.

72. A method of degrading a persistent/toxic organo-halogen into safer form(s) which includes, at elevated temperatures (eg; as in, say, a ball mill above, say, 70 °C), vigorously mixing the organo-halogen with (in any order if sequential, or simultaneously) reagents:

(I) urea or iron sand or steel makers slag,

(II) (A) if (I) is urea, iron sand and/or a source of a reactive metal or (B) if (I) is iron sand, a suitable amide and/or urea, or

(C) if (I) is steel makers slag, a suitable amide and or urea, and

73. A method as claimed in claim 72 wherein there is further (III) an acid.

74. A method as claimed in claim 73 wherein the acid is acetic acid.

75. A method as claimed in claim 74 wherein other reagents may be included.

76. The present invention also consists in reaction products or detoxification media and/or soil resulting from a process or procedure of the present invention.