CN102296182A

CN102296182A - Method for recovering rare earth elements from waste rare earth element grinding materials

Info

Publication number: CN102296182A
Application number: CN2011102244079A
Authority: CN
Inventors: 冀代雨; 张存瑞; 冀代明; 郝喜平
Original assignee: Baotou Xinyuan Rare Earth And Hi-Tech New Material Co Ltd
Current assignee: Baotou Xinyuan Rare Earth And Hi-Tech New Material Co Ltd
Priority date: 2011-07-28
Filing date: 2011-07-28
Publication date: 2011-12-28

Abstract

The invention relates to a method for recovering rare earth elements from waste rare earth element grinding materials and is characterized in that the method comprises the following steps of: using a ternary mixture of ammonium chloride, magnesium sulfate and sulfuric acid as a decomposer, performing low-temperature roasting and water leaching on the ternary mixture, followed by solvent extraction to prepare mixed rare earth chlorides, and performing liquid-liquid concatenation extraction separation to prepare 99.95-99.99% of rare earth oxide. By the adoption of the technology, the sulfuric acid amount is greatly reduced, the pollution caused by tail gas roasting to the environment is decreased, and the total recovery of rare earth is greater than 90%. In the meanwhile, the mixed rare earth chlorides prepared by extraction can be used to directly prepare the rare earth element grinding materials.

Description

A kind of method that reclaims rare earth element by useless rare earth abrasive substance

Technical field

The present invention relates to a kind ofly reclaim the method for rare earth element, belong to and reclaim wherein from the useless rare earth abrasive substance of exhausted that the purification again of rare earth element utilizes the field by useless rare earth abrasive substance.

Background technology

Contain the rare earth class polishing material of cerium because the polishing that polishing velocity is fast, smooth finish, advantage that planeness is high are widely used in the glass substrate of optical lens, liquid-crystal display, panel computer, mobile phone faceplate, making hard disk.The consumption of global rare earth class polishing material in 2010 reaches 30,000 tons.Wherein the China's Mainland consumption is 22000 tons.The total amount of rare earth of polishing powder from rare earth (TREO)＞86wt%, CeO ₂/ TREO＞55%; La ₂O ₃/ TREO=28-36%; Pr ₆O ₁₁/ TREO=4-7%; F=4-7.5%.Polishing powder from rare earth in use at first water want the furnishing slurries, solid content is between 5-20wt%.The mechanism of polishing is the chemical-mechanical polishing principle, promptly because CeO ₂Be face-centered cubic crystal, its Mohs' hardness is between 6.5-7, and polished glass hard (HRC65 is between 6.2-6.5, so cerium oxide can grind away the glass surface protuberance, this is the mechanical polishing principle.Owing to contain the fluorine of 4-7.5wt% in the polishing powder from rare earth, and the base material of glass is SiO ₂So, when polishing, have following reaction to take place:

SiO ₂+4HF＝SiF ₄↑+2H ₂O

This reaction is owing to there is SiF ₄Gas produces, and is irreversible reaction, this both chemical rightenning principle.

Along with the drawing small of the increase cerium oxide particle that recycles number of times of polishing slurries, the consumption polishing powder of fluorine loses usefulness.To change or replenish new polishing powder this moment.Mixture of organic substance such as glass micro mist under polishing powder that lost efficacy and the throwing and the urethane under the polishing pad upthrow, wool pad are through precipitation, and filter press reclaims.

The main component of reclaimed materials such as following table:

The main component of table 1. reclaimed materials (wt%)

As can be seen from the above table, the total amount of rare earth of reclaimed materials is very low, and non-rare earth impurity is very high.As average total amount of rare earth (TREO) 90wt% that presses polishing powder from rare earth calculates, domestic annual 22000 tons consumption can produce more than 76000 ton of the discarded polishing powder from rare earth of total amount of rare earth 26wt%, contain 19800 tons of rare earth oxides, and this solid waste can cause environmental problem because contain the fluorine of 1.6wt%, is the problem that users at home and abroad need solve always.Moreover in short supply along with rare earth resources is necessary this kind waste material is thoroughly reclaimed, utilizes.

Patent 1246407C discloses a kind of renovation process of the polishing powder from rare earth that lost efficacy, this method is to handle by the physical chemistry to the inefficacy polishing powder from rare earth, polishing powder effective constituent regeneration polishing powder wherein is used, is not used and will rare earth element wherein do not extract.

The treatment process of traditional rare earth ore concentrate is vitriol oil high-temperature roasting.Because the rare earth ore concentrate main component is hamartite, monazite, iron ore, fluorite, silica, also has the thorium that exists with phosphoric acid salt.This technology does not enter in the infusion in order to make thorium, takes high temperature (greater than 800 ℃) roasting, and the thorium pyrophosphate of thorium generation this moment indissoluble and metaphosphoric acid thorium be ThP both ₂O ₇And Th (PO ₃) ₄, in follow-up flow process, do not leached, avoided pollution.But sulfuric acid part when high-temperature roasting directly evaporate in the atmosphere, and part is decomposed into SO ₃Form acid gas environment is caused severe contamination.Consume in order to replenish this part simultaneously, the sulfuric acid that is added must be excessive.Press current technology condition ore deposit acid weight ratio 1: (1.2-1.4), ore deposit middle-weight rare earths oxide compound 50wt%, concentrate per ton need be with the sulfuric acid of 92wt%, according to following formula

RE ₂O ₃+3H ₂SO ₄＝RE ₂(SO4) ₃+3H ₂O

500/169＝2.96x10 ³Mole

2.96x1.5＝4.44x10 ³Mole

Sulfuric acid=920/980=9.39x10 of 92wt% per ton ³Mole

So concentrate per ton sulfuric acid=4.44x10 ³/ 9.39x10 ³=0.46 ton

Actual amount 1.2-1.4 ton sulfuric acid.Excessive 1.2-0.46=0.74 ton

Excessive 0.74/0.46=160.87%, an excessive part part consumes on non-rare-earth mineral, part volatilization, a part is at high temperature divided and is taken off.

Summary of the invention

In view of the above problems, the purpose of this invention is to provide and a kind ofly reclaim the method for rare earth element by useless rare earth abrasive substance, can reclaim wherein rare earth element fully with present method, its product purity can reach 99.95-99.99wt%.

Originally the invention provides a kind ofly with chlorine +sal epsom+vitriol oil low-temperature bake water logging, in the magnesium oxide and filtering and impurity removing, sulfuric acid system extraction back extraction prepares mixed chlorinated rare earth, and extracting and separating is produced the method for high-purity rare-earth compound.Technical scheme of the present invention mainly comprises the steps:

In the useless rare earth abrasive substance mixture that reclaims according to the content of rare earth oxide wherein, with the Lvization that adds, sal epsom, the vitriol oil is (6.5～7) by weight:1:(1.6～1.8): (5～6), optimum proportion is 6.8:1:1.65:5 mixed is even, 340～420 ℃ of of of of of of of roastings 1～2 hour, 380 ℃ of of of of of of of optimum calcination temperatures, best roasting time is 1.5 hours, with this roasting mixture normal temperature water logging, infusion is in magnesium oxide and filter, filtrate is through the full extraction of PC-88A (2-ethylhexyl phosphonic acid single 2-ethyl hexyl fat), the hydrochloric acid back extraction prepares mixed chlorinated rare earth solution, prepares single rare earth oxide compound or mixed rare-earth oxide through extracting and separating again.

The mixed chlorinated rare earth solution of above-mentioned preparation precipitates, fluoridizes, calcines through Tan Suan Qing , and crushing and classification can directly be prepared the rare earth abrasive substance.

The described vitriol oil is the sulfuric acid that concentration is not less than 92wt%.

Described roasting roasting is static roasting.

Described useless rare earth abrasive substance mixture is meant total amount of rare earth (TREO) greater than 17wt%, CeO ₂/ TREO＞50%, igloss 45-55%, gross activity is less than the mixture of 50Bq/kg.

In order to reduce sulfuric acid consumption, reduce and pollute the method that adopts the combination decomposition agent among the present invention, the principle of this method is that:Lvization at high temperature is decomposed into ammonia and hydrogenchloride, and hydrogenchloride forms the rare earth chloride of solubility with the rare earth oxide effect.

RE ₂O ₃+HCL＝RECL ₃+H ₂O

Sal epsom is with the reaction of rare earth oxide:

3MgSO ₄+RE ₂O ₃＝RE ₂(SO ₄)+3MgO

The magnesium oxide that generates has reduced the acidity of infusion, has reduced magnesian consumption.

Advantage of the present invention is: present method greatly reduces the vitriolic consumption, has reduced the pollution of roasting tail gas to environment, and the rare earth total recovery is greater than 90%.Simultaneously, the mixed rare earth chlorides of extraction preparation also can directly prepare the rare earth abrasive substance.

Description of drawings

Fig. 1 is a process flow sheet of the present invention.

Embodiment

Embodiment 1.

2 tons of useless polishing material mixtures, TREO=17wt%, 280 kilograms of the industrial sulphuric acids of adding 92wt%, 50 kilograms of technical pure Lvization , 85 kilograms in sal epsom stirs, 350 ℃ of of of of of of and puts into the iron saggar and burns 2 hours for, drop to room temperature and take out, Mechanical Crushing is inserted 20m to 80 orders³The glass fiber reinforced plastic water immersion trough adds 12m ³Water is opened and is stirred water logging 40 minutes, adds magnesium oxide and adjusts pH value to 2.5～3, filter press, filter cake 3m for 50 kilograms ³Wash once, washing lotion is incorporated in the infusion.Measure REO=4.8wt% in the washing back filter cake (110 ℃ of dry backs), REO=19.5g/L in the immersion liquid.

As feed liquid, carry out solvent extraction with above-mentioned infusion, concrete processing parameter: organic phase PC-88A, 1.5mole, kerosene are thinner, the sodium hydroxide saponification, saponification deg 0.55mole, sour regurgitation concentration is 4mole hydrochloric acid.20 grades of total progression, 400 liters of extraction tank volumes (mixing section), progression is divided 6 grades of extractions, washs 8 grades, and 4 grades of back extractions are washed 2 grades.

Concrete processing parameter stream ratio:

Vs: V _f: Vw: V _R=55: 70: 5: 5 (rise/minute)

The quality index such as the table 2 of strip liquor (re chloride)

Table 2. re chloride) quality index (g/L)

REO	La ₂O ₃/REO	CeO ₂/REO	Pr ₆O ₁₁/REO	Nd ₂O ₃/REO
					246	64.5	174.2	6.9	0.4
Fe ₂O ₃	CaO	MgO	PbO
					0.021	0.086	0.017	0.0035

The rare earth yield: above-mentioned flow process obtains 724 kilograms of dried slags, slag middle-weight rare earths total amount 4.6wt%, thus 33.3 kilograms of slag middle-weight rare earths, yield 90.2%.

With this rare earth chloride is feed liquid, through two sections totally 220 grades of liquid-liquid extractions separate preparation rare earth single rare earth muriates, through the yellow soda ash precipitation, high purity lanthanum oxide, cerium oxide, Praseodymium trioxide neodymium are prepared in 1000 ℃ of calcinations.Purity is measured with the PESCIEX ELAN 6100ICP-MS of U.S. PE company.The result shows that lanthanum trioxide purity reaches 99.95%; Cerium oxide purity reaches 99.99%, and measurement result sees Table 3.

The quality index of table 3. lanthanum trioxide, cerium oxide

Embodiment 2.

2 tons of useless polishing material mixtures, TREO=26wt%, 400 kilograms of the industrial sulphuric acids of adding 92wt%, 80 kilograms of technical pure Lvization , 130 kilograms in sal epsom stirs, 380 ℃ of of of of of of and puts into the iron saggar and burns 2 hours for, and all the other steps are with embodiment 1.

The rare earth yield: above-mentioned flow process obtains 689 kilograms of dried slags, slag middle-weight rare earths total amount 4.2wt%, thus 28.93 kilograms of slag middle-weight rare earths, yield 94.4%.

The quality index such as the following table of strip liquor (re chloride):

Table 4. re chloride) quality index (g/L)

REO	La ₂O ₃/REO	CeO ₂/REO	Pr ₆O ₁₁/REO	Nd ₂O ₃/REO
					253.8	62.1	182.3	5.4	0.6
Fe ₂O ₃	CaO	MgO	PbO
					0.015	0.056	0.006	0.0011

The above feed liquid quality index through further separating the lanthanum trioxide that obtains, cerium oxide is as follows:

The quality index of table 5. lanthanum trioxide, cerium oxide (wt%)

Claims

1. method that reclaims rare earth element by useless rare earth abrasive substance, it is characterized in that:in the useless rare earth abrasive substance mixture that reclaims according to the content of rare earth oxide wherein, with the Lvization that adds, sal epsom, the vitriol oil is (6.5～7) by weight:1:(1.6～1.8): the mixed of (5～6) is even, 340～420 ℃ of of of of of of of roastings 1～2 hour, with this roasting mixture normal temperature water logging, infusion is in magnesium oxide and filter, filtrate is through the full extraction of PC-88A (2-ethylhexyl phosphonic acid single 2-ethyl hexyl fat), the hydrochloric acid back extraction prepares mixed chlorinated rare earth solution, prepares single rare earth oxide compound or mixed rare-earth oxide through extracting and separating again.

2. the method by useless rare earth abrasive substance recovery rare earth element according to claim 1, it is characterized in that:the Lvization that the useless rare earth abrasive substance mixture of recovery adds together, sal epsom, the vitriol oil were by weight 6.8:1:1.65:5 mixed.

3. the method by useless rare earth abrasive substance recovery rare earth element according to claim 1 is characterized in that: 380 ℃ of described maturing temperatures.

4. the method by useless rare earth abrasive substance recovery rare earth element according to claim 1, it is characterized in that: described roasting time is 1.5 hours.

5. the method by useless rare earth abrasive substance recovery rare earth element according to claim 1, it is characterized in that: described roasting is static roasting.

6. according to claim 1,2,3,4 or 5 described methods by useless rare earth abrasive substance recovery rare earth element, it is characterized in that: described useless rare earth abrasive substance mixture is meant total amount of rare earth (TREO) greater than 17wt%, CeO ₂/ TREO＞50%, igloss 45-55%, gross activity is less than the mixture of 50Bq/kg.