JPH10280060A - Method for recovering raw material for polishing material from waste cerium polishing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the degradation in grade occurring in impurities, such as iron and aluminum, and to effectively recover rare earths mainly composed of cerium by adding an org. flocculating agent to a waste polishing material slurry, stirring the polishing material and subjecting the material to sepn. of solid from the liquid after pH adjustment. SOLUTION: The waste polishing material slurry is put into a stirring vessel 1 and the org. flocculating agent is added at 0.005 to 1.0% to the solid of the polishing material from an aq. flocculating agent soln. tank 2. An aq. acidic or alkaline soln. is added from a tank 3 into the slurry under stirring by a stirring machine 4 and is subjected to pH adjustment. The slurry is then subjected to the sepn. of the solid from the liquid by stopping the stirring and resting the slurry after the completion of the adjustment. Supernatant water is thereafter put into a drain receiving vessel 15 by pump 6 and a spigot is sent to a filter press 5 to filter and dehydrate the slurry. The rare earth cake is recovered into a cake accepting vessel 14. The range of the pH adjustment varies with the kinds of the slurry, the objects for polishing and the kinds of the org. flocculating agent and, therefore, the range is properly determined by performing a prior test.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering abrasive raw materials from waste cerium abrasive generated in a polishing process of glass or the like using cerium abrasive.

[0002]

2. Description of the Related Art Cerium oxide abrasives of about 3000 tons are used annually to polish polishing glass and optical glass. At present, almost all used cerium abrasives are discarded. However, these used cerium abrasives (waste cerium abrasives) contain rare earths (rare earth elements) such as lanthanum and neodymium, such as about 2000 tons of cerium, and these waste cerium abrasives It is desired from the viewpoint of securing stable rare earth resources to collect rare earths from uranium and effectively use them as cerium abrasives.

[0003] In view of the above, when recovering waste cerium abrasive, it is desirable to avoid contamination of rare earths such as aluminum and iron with impurities that would cause problems in the recycling (refining). Therefore, when these impurities are present, it is necessary to remove them before recycling, which requires a large removal cost. Conventionally, an inorganic coagulant such as PAC (polyaluminum chloride) which has been used as a coagulant at the time of solid-liquid separation of a waste cerium abrasive slurry is not preferable from the viewpoint of mixing of the above impurities.

[0004]

An object of the present invention is to recover rare earth from waste cerium abrasive without deteriorating the quality of rare earth (mainly cerium).
The purpose is to perform collection efficiently.

[0005]

Accordingly, the present invention provides a waste cerium abrasive slurry containing an organic coagulant, stirring the mixture,
This is a method for recovering rare earth from waste cerium abrasive, wherein H-adjustment is performed and then solid-liquid separation is performed.

Further, the present invention is the above-mentioned method for recovering rare earth from waste cerium abrasive, characterized in that an organic coagulant is added in an amount of 0.005% to 1.0% based on the solid material of the abrasive. . When the addition amount of the organic flocculant is 0.005% or less, the formation of flocs in the slurry is weak, and the solid-liquid separation property and the clarity of the supernatant are poor. On the other hand, when the addition amount of the organic flocculant is 1.0
% Or more, the viscosity of the slurry is high, the filtration and dewatering properties are deteriorated, the transport piping is clogged, and the handling is difficult. Note that a particularly preferable range of the amount of the added organic coagulant is 0.02% to 0.2%.

When the waste cerium abrasive slurry used for hard disk polishing is used for pH adjustment, as shown in FIG.
In the case of any of the cationic organic flocculants, pH = 4
No floc is formed in the range of ~ 12, and the solid-liquid separation property and the clarity of the supernatant are poor. On the other hand, at pH = 0 or less, the abrasive dissolves. Therefore, in this case, pH = 0 to 4, pH = 12
It is necessary to do above. Next, when the waste cerium abrasive slurry used for polishing the glass for LCD is used, FIG.
As shown in the figure, in the case of a nonionic organic flocculant, pH =
Floc was formed between 0 and 10, and the solid-liquid separation property and the clarity of the supernatant were good. Further, in the case of an anionic organic flocculant, floc is generated only between pH = 0 to 3,
The solid-liquid separation property and the clarity of the supernatant were good. On the other hand, in the case of the cationic organic flocculant, no floc is generated in the whole pH range, and the solid-liquid separation property and the clarity of the supernatant are poor. Next, L
When the waste cerium abrasive slurry used for polishing the glass for CD / TFT is used, as shown in FIG. 4, in the case of a nonionic organic flocculant, flocs are generated in the entire pH range,
The solid-liquid separation property and the clarity of the supernatant were good. In addition, in the case of anionic and cationic organic flocculants, flocs were generated in all pH ranges, although slightly weaker than nonionic organic flocculants, and solid-liquid separation properties and clarity of the supernatant were good. . From the above, the range of pH adjustment varies depending on the type of waste cerium abrasive slurry to be polished, the object to be polished, and the type of organic coagulant. It was found that good solid-liquid separation properties and clarity of the supernatant could be obtained without using.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a process for recovering a rare earth from waste cerium abrasive according to an embodiment of the present invention. The waste abrasive slurry is put into the stirring tank 1, and a predetermined amount of the organic coagulant aqueous solution is added from the coagulant aqueous solution tank 2 to the stirring tank 1 through the valve 8. Next, an acidic aqueous solution or an alkaline aqueous solution is added from the tank 3 containing the acidic or alkaline aqueous solution while watching the pH meter 9. This operation is performed while stirring the slurry with the stirrer 4. When the pH adjustment is completed, stirring is stopped, the slurry is allowed to stand, and solid-liquid separation is performed. The clear supernatant liquid is withdrawn from the pump 6 through the valves 10 and 12 to the pump 15, and then the spigot (sludge) is sent from the pump 6 to the filter press 5 through the valves 11 and 12 to be filtered and dewatered.
The filtrate separates as 15 and the cake as 14.

[0009]

The present invention will be specifically described below based on examples and comparative examples.

Example 1 A nonionic organic coagulant (polyacrylamide) 0.1% aqueous solution 60 l was added to 3 m 3 of waste cerium abrasive slurry (slurry concentration 100 g / l) used for hard disk polishing.
Is added and stirred. The pH at this time was 9. Subsequently, 10 l of 10% hydrochloric acid was added to adjust the pH to 2.6, and stirring was stopped. The solid formed flocs within 1 minute.
After draining the clear supernatant, the sediment was filtered and dehydrated by a filter press. The water content of the obtained 420 kg cake is 29% and has a large dehydration effect, and the analysis values are as shown in Table 1. It was almost the same as the analysis value of the slurry before treatment, and there was no contamination by impurities. Similar results were obtained using anionic or cationic organic flocculants.

[0011]

[Table 1]

Example 2 To 2.5 m 3 of waste cerium abrasive slurry (slurry concentration 120 g / l) used for hard disk polishing, 120 l of a 0.05% aqueous solution of a nonionic organic coagulant (polyacrylamide) was added and stirred. The pH at this time was 9. Subsequently, 130 l of a 10% aqueous solution of caustic soda was added to adjust the pH to 13 and stirring was stopped. The solid formed flocs within 5 minutes. After draining the clear supernatant, the precipitate was filtered and dehydrated with a filter press. 48 obtained
The water content of the 0kg cake is 37% and the dewatering effect is great.
The analysis values are as shown in Table 1. It was almost the same as the analysis value of the slurry before treatment, and there was no contamination by impurities. Similar results were obtained using anionic or cationic organic flocculants.

Comparative Example 1 To 3 m3 of waste cerium abrasive slurry (slurry concentration: 100 g / l) used for hard disk polishing, 500 l of an aqueous solution of an inorganic coagulant (PAC) was added. It was filtered and dehydrated by a filter press. The water content of the obtained 630 kg cake was 45%. The analytical values are as shown in Table 1. The increase of aluminum was remarkable.

[0014]

As described above, according to the method of the present invention, no inorganic coagulant is used when recovering the abrasive raw material from the waste cerium abrasive, so that it is caused by impurities such as iron and aluminum. Rare earth (mainly cerium) grade does not decrease. Further, since the amount of acid / alkali used for pH adjustment is small, the increase in the amount of slurry liquid is small. Also, since there is little hydroxide such as aluminum in the cake, there is little water in the cake, and handling including transportation is easy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a process for recovering abrasive raw materials according to the present invention.

FIG. 2 is a solid-liquid separation characteristic diagram (waste cerium abrasive slurry used for hard disk polishing).

FIG. 3 is a graph showing solid-liquid separation characteristics (waste cerium abrasive slurry used for polishing glass for LCD).

FIG. 4 is a solid-liquid separation characteristic diagram (waste cerium abrasive slurry used for polishing glass for LCD / TFT).

[Explanation of Signs] 1 ... stirring tank, 2 ... flocculant aqueous solution tank, 3 ... acid and alkali tank, 4 ... stirrer, 5 ... filter press, 6 ... pump, 7, 8, 10, 11, 12, 13 ... valve , 9 ...
pH meter, 14: cake receiving tank, 15: drainage receiving tank.

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[Procedure amendment]

[Submission date] May 20, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction contents]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering abrasive raw materials from waste cerium abrasive generated in a polishing process of glass or the like using cerium abrasive.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art About 3000 tons of cerium oxide abrasives are used annually for polishing polished plate glass, optical glass and the like. At present, almost all used cerium abrasives are discarded. However, these used cerium abrasives (waste cerium abrasives) contain about 3000 tons of cerium and other rare earth elements (rare earth elements) such as lanthanum and neodymium. It is desired from the viewpoint of securing stable rare earth resources to collect rare earths from uranium and effectively use them as cerium abrasives.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

Further, the present invention is the above-mentioned method for recovering rare earth from waste cerium abrasive, characterized in that an organic coagulant is added in an amount of 0.005% to 1.0% with respect to the solid matter of the abrasive. . When the addition amount of the organic flocculant is 0.005% or less, the formation of flocs in the slurry is weak, and the solid-liquid separation property and the clarity of the supernatant are poor. On the other hand, when the addition amount of the organic flocculant is 1.0
% Or more, the viscosity of the slurry is high, the filtration and dewatering properties are deteriorated, the transport piping is clogged, and the handling is difficult. Note that a particularly preferable range of the amount of the added organic coagulant is 0.02% to 0.2%.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C09K 3/14 550 C22B 3/00 Q

Claims (2)

[Claims] 1. A method for recovering abrasive raw material from waste cerium abrasive, comprising adding an organic flocculant to the waste cerium abrasive slurry, stirring the mixture, performing pH adjustment, and then performing solid-liquid separation. 2. An organic coagulant is added to the abrasive solids.
2. The method for recovering abrasive raw materials from waste cerium abrasive according to claim 1, wherein 0.005% to 1.0% is added.