CN106498189A - A kind of recovery method of discarded polishing powder from rare earth - Google Patents

Abstract

A method for recovering waste rare earth polishing powder, comprising the following steps: weighing waste rare earth polishing powder, a reducing agent and a strong base according to the proportion, mixing them evenly, and performing a reduction reaction at 600-800°C for 60-240 minutes to obtain a reduction product Quenching the reduction product to room temperature with water to obtain a cooled product; performing hydrocyclone separation on the cooled product to obtain a mixture of rich rare earth material and silicate aqueous solution and metallic lead; the mixture of silicate aqueous solution and rich rare earth material is filtered to obtain Aqueous silicate solutions and rare earth-rich materials. The invention solves the environmental pollution caused by the lead element in the waste rare earth polishing powder, and at the same time realizes the resource utilization of valuable components rare earth, lead and silicon in the waste rare earth polishing powder, and the lead content in the rich rare earth material after the technology of the invention can be reduced Negligible, the leaching toxicity of heavy metals in rare earth-rich materials meets the national standards, and realizes the harmless, reduction and resourceful treatment of waste rare earth polishing powder, which is in line with my country's goal of developing circular economy and energy conservation and emission reduction.

Description

A kind of recovery method of waste rare earth polishing powder

Technical field:

The invention belongs to the technical field of hazardous solid waste treatment, and in particular relates to a recovery method of waste rare earth polishing powder.

Background technique:

The most important process in material surface processing technology is the polishing process, and polishing powder is one of the key materials in the polishing process, which has a great impact on the quality of the polished product. As an important optical glass polishing material, rare earth polishing powder has many advantages, such as: good crystal shape, good chemical activity, high density and hardness, high polishing efficiency, stable layer photometry and long service life, so it is called "King of polishing powder", and gradually replaced other polishing powder materials and has developed rapidly in the polishing industry. It is widely used in the fine grinding of optical and photoelectric glass, jewelry, building materials, molds and precision instruments.

With the rapid development of optical and electronic information science and technology, the demand for optical glass is increasing year by year, which drives the development of rare earth polishing powder industry. In 2005, the global market demand for rare earth polishing powder was about 20,000 tons, and the consumption of rare earth polishing powder in my country was about 10,000 to 11,000 tons. The largest country in the production and use of polishing powder. In 2011, the consumption of rare earth polishing powder in my country reached 20,000 tons. In 2017, the consumption of rare earth polishing powder in my country is expected to reach more than 100,000 tons. As a major producer of rare earths in my country, the production of rare earth polishing powder has unique advantages, which has driven the development and growth of the polishing industry. However, with the increase in the amount of rare earth polishing powder, the amount of waste rare earth polishing powder is also increasing year by year. Due to the waste rare earth polishing powder It not only contains polishing powder raw materials, but also contains optical glass components. Optical glass contains a large amount of lead. According to relevant research results, lead-containing glass is highly toxic. Although it exists in the form of vitreous body, once it enters water or soil In the process, it will pollute the water body and soil, enter the human body through the food chain, and eventually cause harm to human health. In view of the non-renewability of rare earths and the pollution of heavy metals to the environment, if they can be recycled and reused, it is of great significance for sustainable development and environmental protection.

What the Chinese patent (publication number is CN104371555A) describes is to adopt nitric acid and hydrogen peroxide to dissolve the rare earth oxide in the waste rare earth polishing powder under the condition of heating, adjust the pH value of the solution with ammonia water, then add under the condition of heating The suspension of hydrogen peroxide and Ce(OH) ₄ precipitates the rare earth, and the rare earth oxide is obtained after separation and roasting. This patent will consume a large amount of nitric acid in the process of leaching rare earth elements, and lead will also be dissolved at the same time, resulting in the loss of lead, which is not suitable for the extraction of heavy metal lead and rare earth elements. The Chinese patent (publication number CN101613802A) describes that the network structure of the glass is destroyed by using the vacuum carbothermal reduction method under high temperature and vacuum conditions, and the lead in the glass is reduced by carbon. This patent requires harsh reaction conditions such as high temperature conditions (temperature is 1000° C.) and vacuum (system pressure is 10 Pa) and supporting production equipment, so it is difficult to realize industrial production. What the Chinese patent (publication number is CN102051487A) describes is to mix waste CRT glass powder, activated carbon and strong alkali, and after melting and reacting, separate crude lead, lye and alkali slag, then use dilute hydrochloric acid to soak the alkali slag to extract the residual lead, this patent does not reduce the lead through deep reduction technology, but also needs to use hydrochloric acid to post-treat the alkali slag, which consumes a lot of hydrochloric acid. After analysis, this patent is not applicable to the separation of rare earth, metal lead and silicon.

Invention content:

The object of the present invention is to provide a recovery method of waste rare earth polishing powder, which realizes the harmless, reduction and recycling treatment of waste rare earth polishing powder, and meets the goals of developing circular economy and energy saving and emission reduction in my country.

To achieve the above object, the present invention adopts the following technical solutions:

A kind of recovery method of waste rare earth polishing powder, comprises the following steps:

(1) Take the waste rare earth polishing powder, reducing agent and strong alkali, and mix them uniformly to obtain a mixture; wherein: the waste rare earth polishing powder contains ceria and glass powder, and the described glass powder contains lead oxide and Silicon; the amount added is in molar ratio, lead oxide in the waste rare earth polishing powder: solid carbon in the reducing agent=(1: 1.24)～(1: 3.52); silicon dioxide in the waste rare earth polishing powder: strong alkali=(1: 5.05 )～(1∶9.47);

(2) placing the mixture in a reaction container, performing a reduction reaction to obtain a reduction product; wherein: the reduction reaction temperature is 600-800° C., and the reduction reaction time is 60-240 minutes;

(3) water quenching the reduction product to room temperature to obtain a cooled product;

(4) The cooled product is subjected to hydrocyclone separation to obtain a mixture of rare earth-rich material and silicate aqueous solution, and metallic lead;

(5) The mixture of the aqueous silicate solution and the rare earth-rich material is filtered to obtain the aqueous silicate solution and the rare earth-rich material.

In the step (1), the particle size of the waste rare earth polishing powder is below 20 μm.

In the step (1), the particle size of the reducing agent is below 120 mesh.

In the step (1), the reducing agent is one of activated carbon powder, coke powder or coal powder.

In the described step (1), the strong base is sodium hydroxide or potassium hydroxide.

In the step (1), the silicate aqueous solution is an aqueous sodium silicate solution or an aqueous potassium silicate solution.

In the described step (1), the mixing operation is carried out in a mixer.

In the step (2), the mixture is placed in a magnesia crucible, and the magnesia crucible is placed in a reaction vessel for reduction reaction.

In the described step (2), the reaction vessel is a heating furnace.

In the described step (2), the heating furnace is a muffle furnace.

During the reduction process, the main reactions involved are as follows:

PbO+C=Pb+CO

2PbO+C＝2Pb+CO ₂

PbO+CO=Pb+CO ₂

SiO ₂ +2NaOH=Na ₂ SiO ₃ +H ₂ O

SiO ₂ +2KOH=K ₂ SiO ₃ +H ₂ O

The patented technology can effectively separate the rare earth, lead and silicon elements in the waste rare earth polishing powder.

The basic principle of the main process of the method provided by the invention is as follows:

The lead element in the waste rare earth polishing powder exists in the glass powder in the form of network modification, and the rare earth exists independently in the form of oxide. However, this patent destroys the network structure of the glass body by adding a strong alkali, and generates a silicate phase with a low melting point by the reaction of the strong alkali with silicon dioxide, and releases lead oxide from the stable glass phase network structure, so as to strengthen the glass powder The purpose of the low-temperature deep reduction of lead elements is to use low-temperature reduction technology to control the volatilization behavior of lead elements during the reduction process, and to provide good thermodynamic conditions for strengthening the low-temperature deep reduction technology of lead elements while destroying the glass phase network structure through strong alkali; On the other hand, the low-melting silicate phase formed by the reaction of strong base and silica not only creates a molten liquid environment during the reduction process, but also provides a good kinetic condition for the polymerization growth of metallic lead. The existence of the state silicate phase system can prevent the inward diffusion of oxygen, and can also effectively inhibit the volatilization of metallic lead, thereby improving the yield of metallic lead; activated carbon powder, coke powder and coal powder are known reducing agents. It is mainly used to deeply reduce the lead element in the waste rare earth polishing powder to form metallic lead; the hydrocyclone separation technology is mainly based on the difference in specific gravity of the substance, and the centrifugal force generated during the hydrocyclone separation process is different, thereby realizing the waste rare earth polishing powder. The effective separation of rare earth, lead and silicon elements finally achieves the purpose of comprehensive utilization of waste rare earth polishing powder.

Beneficial effects of the present invention:

(1) The present invention can effectively recycle cerium oxide and leaded glass powder (lead and silicon element) in the waste rare earth polishing powder, not only can solve the pollution of the heavy metal lead element in the waste rare earth polishing powder to the environment, but also realize the waste Resource utilization of valuable components in rare earth polishing powder;

(2) Through the raw material ratio of the present invention and the setting of the reduction reaction time, the reduction reaction is more thorough, and lead oxide can be completely reduced to metallic lead.

(3) After being treated by the present invention, the recovery rate of lead will reach more than 99.9%, and the total amount of lead in rare earth-rich material and silicate aqueous solution is lower than 0.05%, and the obtained silicate aqueous solution can be used as industrial raw material through concentrated crystallization treatment use. Therefore, the purpose of harmless, reduction and resource treatment of lead-containing waste rare earth polishing powder is realized, which is in line with the goals of developing circular economy and energy saving and emission reduction in my country.

Description of drawings:

Fig. 1 process flow diagram of the recovery method of the waste rare earth polishing powder of the present invention.

detailed description:

The present invention will be described in further detail below in conjunction with embodiment.

The object of the present invention is to provide a new technology for resource utilization of lead-containing waste rare earth polishing powder. The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, so that the advantages and characteristics of the present invention can be more easily used. Those skilled in the art understand that, so that the protection scope of the present invention can be defined more clearly.

In the embodiment of the present invention 1～5:

Crushing, grinding and drying the waste rare earth polishing powder, the particle size is below 20μm;

The chemical composition of waste rare earth polishing powder, as shown in table 1;

The particle size of activated carbon powder, coke powder or coal powder is below 120 mesh.

Table 1

Example 1

A kind of recovery method of waste rare earth polishing powder, comprises the following steps:

(1) Weigh 10.013g of waste rare earth polishing powder, 0.194g of coke powder (89% fixed carbon content) and 17.842g of sodium hydroxide, and mix them uniformly in a mixer to obtain a mixture; wherein: by molar ratio, waste rare earth Lead oxide in the polishing powder: solid carbon in the reducing agent = 1: 2.06; in molar ratio, silicon dioxide in the waste rare earth polishing powder: sodium hydroxide = 1: 5.05;

(2) Place the mixture in a magnesia crucible, place the magnesia crucible in a muffle furnace, and perform a reduction reaction. The reduction reaction temperature is 800° C., and the reduction reaction time is 120 minutes to obtain a reduction product;

(3) water quenching the reduction product to room temperature to obtain a cooled product;

(4) The cooled product is subjected to hydrocyclone separation to obtain a mixture of rare earth-rich material and sodium silicate aqueous solution, and metallic lead; rinse the surface of metallic lead with clear water, and weigh the quality of metallic lead after drying to be 1.433g. The recovery rate is 98.8%;

(5) The mixture of sodium silicate aqueous solution and rich rare earth material is by filtration, obtains sodium silicate aqueous solution and rich rare earth material, and the content of CeO in the rich rare earth material is 12.2%, and the content of lead is lower _than 0.05%.

Example 2

A kind of recovery method of waste rare earth polishing powder, comprises the following steps:

(1) Weigh 10.012g of waste rare earth polishing powder, 0.104g of activated carbon powder (fixed carbon content is 99%) and 17.840g of sodium hydroxide, and mix them uniformly in a mixer to obtain a mixture; wherein: by molar ratio, waste rare earth Lead oxide in the polishing powder: solid carbon in the reducing agent = 1: 1.24; in molar ratio, silicon dioxide in the waste rare earth polishing powder: sodium hydroxide = 1: 5.05;

(2) Place the mixture in a magnesia crucible, place the magnesia crucible in a muffle furnace, and perform a reduction reaction. The reduction reaction temperature is 650° C., and the reduction reaction time is 120 minutes to obtain a reduction product;

(3) water quenching the reduction product to room temperature to obtain a cooled product;

(4) The cooled product is subjected to hydrocyclone separation to obtain a mixture of rare earth-rich material and sodium silicate aqueous solution, and metallic lead; rinse the surface of metallic lead with clear water, and weigh the quality of metallic lead after drying to be 1.431g. The recovery rate is 98.7%;

(5) The mixture of sodium silicate aqueous solution and rich rare earth material is by filtration, obtains sodium silicate aqueous solution and rich rare earth material, and the content of CeO in the rich rare earth material is 16.51%, and the content of lead is lower _than 0.05%.

Example 3

A kind of recovery method of waste rare earth polishing powder, comprises the following steps:

(1) Weigh 10.011g of waste rare earth polishing powder, 0.152g of coal powder (fixed carbon content is 71%) and 24.273g of sodium hydroxide, and mix them uniformly in a mixer to obtain a mixture; wherein: by molar ratio, waste rare earth Lead oxide in the polishing powder: solid carbon in the reducing agent = 1: 1.29; in molar ratio, silicon dioxide in the waste rare earth polishing powder: sodium hydroxide = 1: 6.87;

(2) Place the mixture in a magnesia crucible, place the magnesia crucible in a muffle furnace, and perform a reduction reaction. The reduction reaction temperature is 800° C., and the reduction reaction time is 120 minutes to obtain a reduction product;

(3) water quenching the reduction product to room temperature to obtain a cooled product;

(4) The cooled product is subjected to hydrocyclone separation to obtain a mixture of rare earth-rich material and sodium silicate aqueous solution, and metallic lead; rinse the surface of metallic lead with clear water, and weigh the quality of metallic lead after drying to be 1.427g. The recovery rate is 98.4%;

(5) the mixture of sodium silicate aqueous solution and rich rare earth material is by filtration, obtains sodium silicate aqueous solution and rich rare earth material, and the content of CeO in the rich rare earth material is 17.5%, and the content of lead is lower _than 0.05%.

Example 4

A kind of recovery method of waste rare earth polishing powder, comprises the following steps:

(1) Weigh 10.006g of waste rare earth polishing powder, 0.296g of activated carbon powder (fixed carbon content is 99%) and 33.41g of sodium hydroxide, and mix them uniformly in a mixer to obtain a mixture; wherein: by molar ratio, waste rare earth Lead oxide in the polishing powder: solid carbon in the reducing agent = 1: 3.52; in molar ratio, silicon dioxide in the waste rare earth polishing powder: sodium hydroxide = 1: 9.47;

(2) Place the mixture in a magnesia crucible, place the magnesia crucible in a muffle furnace, and perform a reduction reaction. The reduction reaction temperature is 600° C., and the reduction reaction time is 240 minutes to obtain a reduction product;

(3) water quenching the reduction product to room temperature to obtain a cooled product;

(4) The cooled product is subjected to hydrocyclone separation to obtain a mixture of rare earth-rich material and sodium silicate aqueous solution, and metallic lead; rinse the surface of metallic lead with clear water, and weigh the quality of metallic lead after drying to be 1.432g, metallic lead The recovery rate is 98.8%;

(5) The mixture of sodium silicate aqueous solution and rich rare earth material is by filtration, obtains sodium silicate aqueous solution and rich rare earth material, and the content of CeO in the rich rare earth material is 16.63%, and the content of lead is lower _than 0.05%.

Example 5

A kind of recovery method of waste rare earth polishing powder, comprises the following steps:

(1) Weigh 10.021g of waste rare earth polishing powder, 0.184g of activated carbon powder (fixed carbon content is 99%) and 40.791g of potassium hydroxide, and mix them uniformly in a mixer to obtain a mixture; wherein: by molar ratio, waste rare earth Lead oxide in the polishing powder: solid carbon in the reducing agent = 1: 2.19; by molar ratio, silicon dioxide in the waste rare earth polishing powder: potassium hydroxide = 1: 8.24;

(2) Place the mixture in a magnesia crucible, place the magnesia crucible in a muffle furnace, and perform a reduction reaction. The reduction reaction temperature is 750° C., and the reduction reaction time is 60 minutes to obtain a reduction product;

(3) water quenching the reduction product to room temperature to obtain a cooled product;

(4) The cooled product is subjected to hydrocyclone separation to obtain a mixture of rare earth-rich material and potassium silicate aqueous solution, and metallic lead; rinse the surface of metallic lead with clear water, and weigh the quality of metallic lead after drying to be 1.431g. The recovery rate is 98.6%;

(5) The mixture of potassium silicate aqueous solution and rich rare earth material is by filtration, obtains potassium silicate aqueous solution and rich rare earth material, and the content of CeO in the rich rare earth material is 16.6%, and the content of lead is lower _than 0.05%.

Claims (8)

1. a kind of recovery method of discarded polishing powder from rare earth, it is characterised in that comprise the following steps：

(1) discarded polishing powder from rare earth, reducing agent and highly basic are weighed, and mix homogeneously obtains mixture；Wherein：The discarded rare earth Containing ceria and glass dust in polishing powder, containing lead oxide and silicon dioxide in the glass dust；Addition in molar ratio, Lead oxide in discarded polishing powder from rare earth: solid carbon=(1: 1.24)～(1: 3.52) in reducing agent；Two in discarded polishing powder from rare earth Silicon oxide: highly basic=(1: 5.05)～(1: 9.47)；

(2) mixture is positioned in reaction vessel, carries out reduction reaction, obtain reduzate；Wherein：Reduction reaction temperature is 600～800 DEG C, the reduction reaction time is 60～240min；

(3) by reduzate water quenching to room temperature, cooled product is obtained；

(4) cooled product is carried out rotary filter press, obtains the mixture of rich rare earth material and aqueous silicate solution, and metallic lead；

(5) mixture of aqueous silicate solution and rich rare earth material obtains aqueous silicate solution and rich rare earth material through filtering.

2. the recovery method of discarded polishing powder from rare earth according to claim 1, it is characterised in that in described step (1), Discarded polishing powder from rare earth granularity is below 20 μm.

3. the recovery method of discarded polishing powder from rare earth according to claim 1, it is characterised in that in described step (1), Reducing agent granularity is below 120 mesh.

4. the recovery method of discarded polishing powder from rare earth according to claim 1, it is characterised in that in described step (1), Reducing agent is the one kind in activated carbon powder, coke blacking or coal dust.

5. the recovery method of discarded polishing powder from rare earth according to claim 1, it is characterised in that in described step (1), Highly basic is sodium hydroxide or potassium hydroxide.

6. the recovery method of discarded polishing powder from rare earth according to claim 1, it is characterised in that in described step (1), Married operation is carried out in batch mixer.

7. the recovery method of discarded polishing powder from rare earth according to claim 1, it is characterised in that in described step (2), Mixture is positioned in magnesia crucible, and magnesia crucible is positioned in reaction vessel, carries out reduction reaction.

8. the recovery method of discarded polishing powder from rare earth according to claim 1, it is characterised in that in described step (2), Reaction vessel is heating furnace.