WO1987005226A1 - Protective treatment of coal - Google Patents

Protective treatment of coal Download PDF

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Publication number
WO1987005226A1
WO1987005226A1 PCT/AU1986/000055 AU8600055W WO8705226A1 WO 1987005226 A1 WO1987005226 A1 WO 1987005226A1 AU 8600055 W AU8600055 W AU 8600055W WO 8705226 A1 WO8705226 A1 WO 8705226A1
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WO
WIPO (PCT)
Prior art keywords
coal
mineral oil
paraffinic mineral
treating agent
process according
Prior art date
Application number
PCT/AU1986/000055
Other languages
French (fr)
Inventor
Douglas C. Angelos
Peter J. Scales
Original Assignee
Applied Chemicals Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Applied Chemicals Pty Ltd filed Critical Applied Chemicals Pty Ltd
Priority to PCT/AU1986/000055 priority Critical patent/WO1987005226A1/en
Publication of WO1987005226A1 publication Critical patent/WO1987005226A1/en

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Classifications

    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10LFUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L9/00Treating solid fuels to improve their combustion
    • C10L9/10Treating solid fuels to improve their combustion by using additives

Definitions

  • This invention relates to a protective treatment for coal and a composition for use in that protective treatment.
  • Coal is mined, crushed, stockpiled and transported in extremely large quantities. Exposure to air and moisture promotes exothermic reactions which result in deterioration of the coal and, if the heat is not dispersed, may eventually support combustion. Severe losses may be sustained if effective precautions are not taken.
  • Veneer coating of stockpiles with impervious coatings may be a chemical or tarpaulin type barrier.
  • total treatment of a given quantity of coal involves contacting more than 50% of ,the coal particles therein with a treating agent. Preferably over 75%, and more preferably over 90%, of the particles are so contacted. In a preferred aspect this total treatment involves spraying coal with a chemical treating agent in such manner that all of the coal particles, or at least a large percentage of the finer coal fraction comes into contact with the chemical treating agent.
  • the treating agent is preferably an emulsified hydrocarbon oil, and also containing certain other chemical specialty additives.
  • the agent is diluted in water and is sprayed onto the coal surface.
  • the level of dilution in the water phase is unimportant to the application
  • the level of chemical added to the coal surface depends upon the nature of the coal and may vary, for example, from 15 to 1000 ppm. The broad nature of this addition rate is due to the very diverse nature of the coal types available for treatment.
  • the present invention is a considerable advance in the art because, by total treatment of the coal, it avoids the need for repeating the protective treatment every time the coal is moved.
  • Many coals, such as those coals to be blended and moved repeatedly after mining and crushing are generally precluded from mechanical treatments and may not even be suitable commercial commodities if a real problem exists.
  • Total chemical treatment does not have such prohibitive effects as one treatment is suitable to inhibit self heating through a number of coal movements and stockpile residences. Consequently a coal formerly considered too hazardous to strip and stockpile may now be deemed safe using our total treatment. It follows that many coals precluded from export because of their propensity to self heat may now be considered as a possible viable export commodity.
  • a preferred method of treatment comprises spraying of the coal in a falling stream situation, for example at a conveyor belt junction or conveyor belt transfer point.
  • the treatment may be singular or multiple to achieve the total concentration of chemical on the coal surface that is required.
  • coal is a naturally occurring mineral showing many diverse forms and composition, treatment levels vary accordingly.
  • the treating agent of the invention is preferably a hydrocarbon oil emulsified in water with a cationic emulsifier.
  • the hydrocarbon oil is preferably a paraffinic mineral oil that meets the following specifications:
  • a suitable emulsion may contain
  • Agent C has the following composition:
  • Paraffinic Mineral Oil (CALTEX P300) 36.0% w/w Synthetic Polyolefin (HYVIS) 3.5
  • Alkyldiamine surfactant (DIAMINE BG). 3.3 Commercial Oleine (PRIOLENE 6973) 1.0 Acrylic Thickening Agent (ACRYSOL ICS-I) 0.5
  • agent C In field tests, the ability of agent C to inhibit oxidation in a stockpiling situation was measured. A number of coal shipments were treated with agent C at a dosage rate of approximately 150 ppm (at a cost of A$0.20 per tonne of coal) and the stockpile temperatures monitored as a function of time. The range of heating rates for these shipments are compared to that of the untreated coal, stockpiled under the same climatic conditions, in Table 2. The range of heating rates for a relatively safe storage coal is included in this table for comparison.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)

Abstract

A process and composition for protective treatment of coal comprises applying a chemical treating agent to a major proportion of coal particles in a quantity of coal by sprays (3), (4) directed upon a falling stream of coal. The treating agent is a paraffinic mineral oil emulsified with a cationic emulsifier.

Description

PROTECTIVE TREATMENT OF COAL
This invention relates to a protective treatment for coal and a composition for use in that protective treatment. Coal is mined, crushed, stockpiled and transported in extremely large quantities. Exposure to air and moisture promotes exothermic reactions which result in deterioration of the coal and, if the heat is not dispersed, may eventually support combustion. Severe losses may be sustained if effective precautions are not taken.
The self-heating characteristics of coal have been known for centuries but the mechanism is still not completely understood. Stockpiling techniques which minimize spontaneous combustion are well established but do not entirely overcome the problem. Much greater, difficulties are encountered in the transportation of large quantities of coal, particularly in ships where spontaneous combustion is a major safety hazard in addition to the loss of valuable coal that it represents. The prior art has concentrated on limiting access of oxygen and/or moisture to bulk coal in an attempt to minimize the chemical reactions that cause self heating, while additionally or alternatively providing means to disperse the heat generated, for example by ventilation, so that some oxidation may occur without a dangerous rise in temperature. Some known physical/mechanical methods may be summarized as follows:-
1. Sophisticated stockpile construction with special attention to the even distribution of very fine particulates. This ensures generated heat is evenly distributed throughout the stockpile and not concentrated in an area with an excess of very fine, very high surface are material.
2. Veneer coating of stockpiles with impervious coatings. These may be a chemical or tarpaulin type barrier.
3. Surface compaction using heavy machinery to slow down the ingress of both air and moisture.
4. Stockpile configuration and alignment to minimize the interaction of the stockpile with prevailing winds.
All of the prior art methods involve treatment of the exterior of a stockpile, to provide a physical barrier to the ingress of moisture and air. The effectiveness of such treatments is limited as the barriers are easily broken.
It is an object of the present invention to provide a treatment which is more effective than the prior art.
In accordance with the present invention, treatment of the coal is not confined to the exterior of a heap or stockpile. As all of the coal surface, or at least a major part of it, is treated in accordance with the present invention, we refer to this technique as "total treatment". "Total treatment" of a given quantity of coal involves contacting more than 50% of ,the coal particles therein with a treating agent. Preferably over 75%, and more preferably over 90%, of the particles are so contacted. In a preferred aspect this total treatment involves spraying coal with a chemical treating agent in such manner that all of the coal particles, or at least a large percentage of the finer coal fraction comes into contact with the chemical treating agent. The treating agent is preferably an emulsified hydrocarbon oil, and also containing certain other chemical specialty additives.
In one method of application the agent is diluted in water and is sprayed onto the coal surface. The level of dilution in the water phase is unimportant to the application
* as the water simply provides a vehicle to coat the coal surface. The level of chemical added to the coal surface, as distinct from the level of moisture added, depends upon the nature of the coal and may vary, for example, from 15 to 1000 ppm. The broad nature of this addition rate is due to the very diverse nature of the coal types available for treatment.
Although we do not wish to be limited by any theoretical or postulated mechanism for the observed beneficial effects, we believe that the important improvement in the technology now proposed over conventional methods of combating self heating in coal stockpiles and storage is tied up intimately with the total treatment of the coal surface, rather than just the exterior to the stockpile. We believe that our treatment provides an oil film on the coal surface which aids agglomeration of fine particles to others of the same size and/or to larger particulates in the same system. Both the' oil film and agglomeration appear to assist in the exclusion of moisture and air from the internal coal pore structure and the reduction of the total coal surface area available to external air and moisture ingress, which are prime environmental determinants in coal self heating. The present invention is a considerable advance in the art because, by total treatment of the coal, it avoids the need for repeating the protective treatment every time the coal is moved. Many coals, such as those coals to be blended and moved repeatedly after mining and crushing are generally precluded from mechanical treatments and may not even be suitable commercial commodities if a real problem exists. Total chemical treatment does not have such prohibitive effects as one treatment is suitable to inhibit self heating through a number of coal movements and stockpile residences. Consequently a coal formerly considered too hazardous to strip and stockpile may now be deemed safe using our total treatment. It follows that many coals precluded from export because of their propensity to self heat may now be considered as a possible viable export commodity. The relatively large increases in possible stockpiling life made possible by the present invention will allow for exporters to consider larger bulk shipments with their attendant savings in freight. It follows as a natural corollary to the above that by retarding self heating, original fundamental coal properties are also retained on a relative bases. This suggests that large consumers would possibly aggregate large stockpiles to obviate irregularities of supply, safe in the knowledge that coal properties and thus- the inherent costs involved do not degrade during the subsequent stockpiling period. For producers, the opportunity provides itself to mine and produce on a continuous basis, safe also in the knowledge that their coal would remain within the specifications laid down by the consumer during periods of low demand. This is particularly relevant to steaming coals for power generation i.e. coals of lignitous or a sub-bituminous rank.
The experimental work outlined below, has established that the preferred emulsified hydrocarbon oil of the present invention is the most effective in the retardation of self heating over a range of coal types. Surface active agents were experimentally found less effective, as were polymeric binders, in that, whilst providing pa icle-particle binding in most cases, the very large internal coal porosity was not excluded from the atmosphere. Levels of treatment from 0 to 500 ppm were examined, with effectiveness increasing abruptly in the 0-100 ppm regime and then more slowly after this level of addition. The use of higher dose rates, up to 1000 ppm is appropriate for coals of higher porosity.
In practice a preferred method of treatment comprises spraying of the coal in a falling stream situation, for example at a conveyor belt junction or conveyor belt transfer point. The treatment may be singular or multiple to achieve the total concentration of chemical on the coal surface that is required. As coal is a naturally occurring mineral showing many diverse forms and composition, treatment levels vary accordingly. By use of in line mixing of the
* chemical to the water (carrier) phase, the actual solution strength may be varied by use of a simple dosing pump adjustment. This simple method of application thus becomes part of coal production without adding to physical processing costs i.e. it does not include large capital equipment or labour costs.
Two methods of applying the spray are illustrated in the accompanying drawings.
In Figure 1, coal falls from a feed hopper 1 on to a conveyor 2, and the treating agent is applied via sprays 3, 4.
In Figure 2, at a conveyor transfer point coal falls from an upper conveyor 21 to a lower conveyor 22, and the treating agent is applied via sprays 23 and 24. An alternative spray point is shown at 24A. The treating agent of the invention is preferably a hydrocarbon oil emulsified in water with a cationic emulsifier. The hydrocarbon oil is preferably a paraffinic mineral oil that meets the following specifications:
Colour Less than 1.5
Density 20°C 0.885 - 0.890 Viscosity 55 - 60 cst at 40°
7 - 8 cst at 100°C
Flashpoint 240°C min (COC)
Pour Point -8°C →- - 10°C Carbon Type: - aliphatic 63 - 65%
- naphthenic 27 - 28%
- aromatic 10% max
A suitable emulsion may contain
Component % by Weight
Paraffinic Mineral Oil 35 - 37
(as above)
Synthetic Polyo'lef: Ln 3.5
Alkyldiamine Surfactant 3.0 - - 3.5
Oleine 1.0
Viscosity Modifier 0.5
Hydrochloric Acid 0.4 - - 0.5
Formaldehyde 40% 0.1
Sucrose 0.03
Pink Dye 0.01
Water 54 - 56
Experimental
Using a calorimeter which measures the maximum temperature rise produced in a coal sample under different environmental conditions of humidity, temperature and oxygen content, the maximum temperature rise was determined under oxidizing conditions for four samples of the same coal type, treated with different agents. The results are give in Table 1.
TABLE 1
Max. Temp, Time to Max.
Agen Type Rise (°C) Temp. Rise (min
Untreated, - 3.4 780 A Wetting Agent 3.3 720
B Polymer Dispersant 2.5 780
C (see below) 1.4 660
D Diesel 2.8 690
Agent C has the following composition:
Paraffinic Mineral Oil (CALTEX P300) 36.0% w/w Synthetic Polyolefin (HYVIS) 3.5
Alkyldiamine surfactant (DIAMINE BG). 3.3 Commercial Oleine (PRIOLENE 6973) 1.0 Acrylic Thickening Agent (ACRYSOL ICS-I) 0.5
Commercial HYDROCHLORIC ACID 0.43
SUCROSE 0.03
FORMALDEHYDE 40% 0.10
RHODAMINE B Pink Dye 0.01 WATER 55.13
100.00 All the reagents, were tested on the same coal type at a dosage rate of 500 ppm equivalent to approximately 0.5 litres of agent per tonne of coal. The wetting agent (A) was the only agent tested which did not reduce the maximum temperature rise of the coal to any extent. The superiority of the treating agent according to the invention (agent C) is evident.
In field tests, the ability of agent C to inhibit oxidation in a stockpiling situation was measured. A number of coal shipments were treated with agent C at a dosage rate of approximately 150 ppm (at a cost of A$0.20 per tonne of coal) and the stockpile temperatures monitored as a function of time. The range of heating rates for these shipments are compared to that of the untreated coal, stockpiled under the same climatic conditions, in Table 2. The range of heating rates for a relatively safe storage coal is included in this table for comparison.
TABLE 2
Coal Stockpile Heating Rates
Coal Type Heating Rate (°C/day)
Safe Coal 0.20 - 0.25
Untreated Coal 0.88 - 1.30 Treated Coal 0.46 - 0.56
By lowering the heating rate agent C was found to increase the stockpiling life of the above coal from approximately six weeks to in excess of six months. In addition, the treated coal was observed to stop heating once the stockpile temperature reached approximately 60°C. This was not the case with the untreated coal.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:
1. A process for protective treatment of coal characterised in that a chemical treating agent is applied to a quantity of coal in such manner that at least 50% of the coal particles come into contact with the said treating agent.
2. Process according to Claim 1, in which the treating agent is an aqueous emulsion of a hydrocarbon oil.
3. Process according to Claim 2, in which the treating agent is a paraffinic mineral oil emulsified with a cationic emulsifier.
4. Process according to Claim 3, in which the paraffinic mineral oil meets the following speci ications:-
Colour Less than 1.5
Density 20°C 0.885 - 0.890
^Viscosity 55 - 60 cst at 40°
7 - 8 cst at 100°C
Flashpoint 240UC min (CO
Pour Point -8°C →-- 10°C
Carbon Type:
- aliphatic 63 - 65%
- naphthenic 27 - 28%
- aromatic 10% max
5. Process according to Claim 3, in which the treating. agent comprises the following components:
Component % by Weight
Paraffinic Mineral Oil 35 - 37
(as defined in Claim 4)
Synthetic Polyolefin 3.5
Alkyldiamine Surfactant 3.0 - - 3.5
Oleine 1.0
Viscosity Modifier 0.5
Hydrochloric Acid 0.4 - • 0.5
Formaldehyde 40% 0.1
Sucrose 0.03
Pink Dye 0.01
Water 54 - 56
6. Process according to Claim 3, in which the treating agent comprises the following components:-
Paraffinic Mineral Oil (CALTEX P300) 36.0% w/w
Synthetic Polyolefin (HYVIS) 3.5
Alkyldiamine surfactant (DIAMINE BG) 3.3
Commercial Oleine (PRIOLENE 6973) 1.0
Acrylic Thickening Agent (ACRYSOL ICS-I) 0.5
Commercial HYDROCHLORIC ACID 0.43
SUCROSE 0.03
FORMALDEHYDE 40% 0.10
RHODAMINE B Pink Dye 0.01
WATER 55.13
100.00
7. A composition of qnatter useful for the protective treatment of coal, comprising the following components:-
Component % by Weight
Paraffinic Mineral Oil 35 - 37
Synthetic Polyolefin 3.5
Alkyldiamine Surfactant 3.0 - 3.5
Oleine 1.0
Viscosity Modifier 0.5
Hydrochloric Acid 0.4 - 0.5
Formaldehyde 40% 0.1
Sucrose 0.03
Pi.nk Dye 0.01
Water 54 - 56
in which the paraffinic mineral oil meets the following specification:-
Colour Less than 1.5
Density 20°C 0.885 - 0.890
Viscosity 55 - 60 cst at 40°
7 - 8 cst at 100°C
Flashpoint 240 C min (CO'
Pour Point -8°C →- - 10°C
Carbon Type:
- aliphatic 63 - 65%
- naphthenic 27 - 28%
- aromatic 10% max
8. A composition of matter useful for the protective treatment of coal, comprising the following components:-
Paraffinic Mineral Oil (CALTEX P300) 36.0% w/w
Synthetic Polyolefin (HYVIS) 3.5
Alkyldiamine surfactant (DIAMINE BG) 3.3
Commercial Oleine (PRIOLENE 6973) 1.0
Acrylic Thickening Agent (ACRYSOL ICS-I) 0.5
Commercial HYDROCHLORIC ACID 0.43
SUCROSE 0.03
FORMALDEHYDE 40% 0.10
RHODAMINE B Pink Dye 0.01
WATER 55.13
100.00
PCT/AU1986/000055 1986-03-06 1986-03-06 Protective treatment of coal WO1987005226A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/AU1986/000055 WO1987005226A1 (en) 1986-03-06 1986-03-06 Protective treatment of coal

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/AU1986/000055 WO1987005226A1 (en) 1986-03-06 1986-03-06 Protective treatment of coal

Publications (1)

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WO1987005226A1 true WO1987005226A1 (en) 1987-09-11

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994026404A1 (en) * 1993-05-11 1994-11-24 Colas Danmark A/S An emulsion of oil in water
GB2279079A (en) * 1993-06-15 1994-12-21 Castrol Ltd Aqueous dust suppressant composition comprising oil and emulsifier
WO2017074194A1 (en) 2015-10-30 2017-05-04 Instral Holding B.V. A method of performing a treatment of a particulate raw material

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE513846C (en) * 1925-05-15 1930-12-03 Fritz Lydtin Dr Process for the production of a dust binder for roads, etc.
US2222370A (en) * 1939-03-01 1940-11-19 Gulf Research Development Co Laying dust in coal mines
GB1392984A (en) * 1971-06-14 1975-05-07 Kalk Chemische Fabrik Gmbh Supressing spontaneous ignition of coal
FR2288775A1 (en) * 1974-10-23 1976-05-21 Exxon Research Engineering Co Anti-dusting compsn for powders - comprises aq emulsion of low volatility org liq
DE2538276A1 (en) * 1975-08-28 1977-04-14 Kali & Salz Ag Dust-binding agents for salts and fertilisers - contg. mixts. of paraffins and spindle- or mineral oil
AU1564683A (en) * 1981-12-21 1984-12-13 Atlantic Richfield Company Method and apparatus for producing a dried coal fuel having a reduced tendency to spontaneously ignite from a low rank coal

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE513846C (en) * 1925-05-15 1930-12-03 Fritz Lydtin Dr Process for the production of a dust binder for roads, etc.
US2222370A (en) * 1939-03-01 1940-11-19 Gulf Research Development Co Laying dust in coal mines
GB1392984A (en) * 1971-06-14 1975-05-07 Kalk Chemische Fabrik Gmbh Supressing spontaneous ignition of coal
FR2288775A1 (en) * 1974-10-23 1976-05-21 Exxon Research Engineering Co Anti-dusting compsn for powders - comprises aq emulsion of low volatility org liq
DE2538276A1 (en) * 1975-08-28 1977-04-14 Kali & Salz Ag Dust-binding agents for salts and fertilisers - contg. mixts. of paraffins and spindle- or mineral oil
AU1564683A (en) * 1981-12-21 1984-12-13 Atlantic Richfield Company Method and apparatus for producing a dried coal fuel having a reduced tendency to spontaneously ignite from a low rank coal

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994026404A1 (en) * 1993-05-11 1994-11-24 Colas Danmark A/S An emulsion of oil in water
GB2279079A (en) * 1993-06-15 1994-12-21 Castrol Ltd Aqueous dust suppressant composition comprising oil and emulsifier
GB2279079B (en) * 1993-06-15 1997-09-24 Castrol Ltd A method for suppressing dust
WO2017074194A1 (en) 2015-10-30 2017-05-04 Instral Holding B.V. A method of performing a treatment of a particulate raw material

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