CN103131862B - Extraction of High Purity Rare Earth Oxide from Phosphor Powder Waste by Pretreatment Decomposition - Google Patents

Abstract

The high-purity rare earth oxide is extracted from the fluorescent powder waste by a pretreatment decomposition method, and the high-purity rare earth oxide is extracted from the fluorescent powder waste by the processes of fluorescent powder waste pretreatment, oxidizing roasting, acidolysis, extraction, precipitation and ignition. The invention improves the recovery rate of the rare earth in the waste by controlling the reaction temperature and adding the cosolvent; liquid caustic soda is used as a saponification extracting agent, so that the wastewater is free from ammonia and nitrogen emission, and the environmental pollution is reduced; the quality of the recovered product is improved, the production cost is reduced, and the process technology has certain innovativeness.

Description

Extraction of High Purity Rare Earth Oxide from Phosphor Powder Waste by Pretreatment Decomposition

technical field

The invention relates to the technical field of recycling fluorescent powder waste, in particular to a pretreatment decomposition method for extracting high-purity rare earth oxides from fluorescent powder waste.

Background technique

At present, due to production and use factors, domestic phosphor production and product scrapping amount to hundreds of thousands of tons. Phosphor powder waste generally has a difference in the distribution of rare earths, which can be divided into low-grade and high-grade phosphor waste. However, manufacturers of low-grade phosphor waste can only discard or store them, and can only deal with high-grade phosphor waste. At present, the production process for recovering valuable elements from phosphor waste is usually: roasting→acid dissolution or alkali leaching→purification and impurity removal→extraction separation and purification. There are common problems such as low acid dissolution rate of rare earth waste, and the chemical auxiliary materials used in the recovery of rare earth are finally discharged in the form of ammonia and nitrogen wastewater, resulting in the waste of a large amount of valuable resources and serious pollution to the environment.

Contents of the invention

The technical problem to be solved by the present invention is to provide a pretreatment decomposition method to extract high-purity rare earth oxides from fluorescent powder waste, so as to solve the above-mentioned problems in the background technology.

The technical problem solved by the present invention adopts following technical scheme to realize:

The pretreatment decomposition method extracts high-purity rare earth oxides from phosphor waste, including the following six steps:

(1) Phosphor powder waste pretreatment; add phosphor powder waste to the enamel reaction pot, add water and stir to make a slurry, heat to 40-80°C; slowly add hydrochloric acid to the enamel reaction pot to dissolve and run for 12-20h, after clarification Drain the supernatant; then add tap water for secondary impurity removal, add pure rare earth solution and stir after washing, keep the temperature for 20 to 40 minutes, add oxalic acid to precipitate part of the dissolved rare earth until it is detected that there are no rare earth elements in the clear liquid. Plate and frame filter press for plate and frame filter press, filtrate to wastewater treatment, filter cake to oxidation roasting;

(2) Oxidative roasting: After the pretreated filter cake is mixed with sodium hydroxide solution and mixed evenly, it is roasted and oxidized in a kiln, and the roasting temperature is controlled at 700-900°C, and the heat is kept until the waste is roasted completely;

(3) Acid hydrolysis: Add water to the roasted waste to make a slurry in an acid-dissolving tank, then add hydrochloric acid to dissolve, and add a cosolvent to aid in dissolution, and the solution is filtered through a plate and frame filter press to obtain a rare earth chloride feed liquid, and remove impurities ;

(4) Extraction: use liquid caustic soda as the extraction saponification agent, put liquid caustic soda into the rare earth chloride feed solution and remove impurities to obtain rare earth chloride solution, and achieve no ammonia and nitrogen discharge in wastewater;

(5) Precipitation; Slowly add pure rare earth feed solution and oxalic acid to the rare earth chloride solution obtained in step (4), control the temperature at 60°C to 70°C, and use the reaction kettle and suction filter to conduct rapid precipitation through the precipitant to obtain the rare earth oxalate ;

(6) Burning: use a kiln to burn the rare earth oxalate obtained in step (5) at a high temperature of 1000°C, and then undergo dehydration, carbonization, and oxidation to obtain high-purity rare earth oxides.

Beneficial effect:

The invention improves the recovery rate of rare earths in waste by controlling the reaction temperature and adding co-solvent; adopts liquid caustic soda as a saponification extraction agent, achieves no ammonia and nitrogen discharge in waste water, and reduces environmental pollution; improves the quality of recycled products and reduces production costs , the process technology has a certain degree of innovation.

detailed description

In order to make it easy to understand the technical means, creative features, work flow, and use methods of the present invention to achieve the purpose and effect, the present invention will be further elaborated below.

The pretreatment decomposition method extracts high-purity rare earth oxides from phosphor waste, including the following six steps:

(1) Phosphor powder waste pretreatment; take 300g of phosphor powder waste and add it to the enamel reaction pot, add 800ml of water and stir to make a slurry, then heat to 75°C; slowly add hydrochloric acid to the enamel reaction pot to dissolve and run for 20 hours, and discharge after clarification Add tap water to the supernatant for secondary impurity removal. After washing, add pure rare earth solution and stir. After 35 minutes at 75°C, add oxalic acid to precipitate part of the dissolved rare earth until it is detected that there is no rare earth element in the supernatant. Frame filter press for plate and frame filter press, filtrate to wastewater treatment, filter cake to oxidation roasting;

(2) Oxidative roasting: After the pretreated filter cake is mixed with sodium hydroxide solution and mixed evenly, it is roasted and oxidized in a kiln, and the roasting temperature is controlled at 700-900°C, and the heat is kept until the waste is roasted completely;

(3) Acid hydrolysis: Add 1L of water to the roasted waste in an acid-dissolving tank to make a slurry, then add hydrochloric acid to dissolve, and add a cosolvent to aid in dissolution. The solution is filtered through a plate and frame filter press to obtain a rare earth chloride feed solution. cleaning;

(4) Extraction: use liquid caustic soda as the extraction saponification agent, put liquid caustic soda into the rare earth chloride feed liquid, remove impurities after mechanical stirring to obtain rare earth chloride solution, and achieve no ammonia and nitrogen discharge in wastewater;

(5) Precipitation: Slowly add pure rare earth feed liquid and oxalic acid to the rare earth chloride solution obtained in step (4), control the temperature at 65°C, and use the reaction kettle and suction filter tank to conduct rapid precipitation through a precipitant to obtain rare earth oxalic acid;

(6) Burning: use a kiln to burn the rare earth oxalate obtained in step (5) at a high temperature of 1000°C, and then undergo dehydration, carbonization, and oxidation to obtain high-purity rare earth oxides.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments, and what described in the above-mentioned embodiments and the description only illustrates the principles of the present invention, and the present invention will also have other functions without departing from the spirit and scope of the present invention. Variations and improvements all fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (1)

1. pretreatment decomposition method extracts high purity rare earth oxides from fluorescent powder scrap, it is characterized in that: include following 6 steps:

(1) fluorescent powder scrap pretreatment；Add water in fluorescent powder scrap is added enamel reaction pot after being slurried after stirring, be heated up to 40～80 DEG C；Being slowly added to hydrochloric acid and dissolve operation 12～20h to enamel reaction pot, clarification heel row puts clear liquid；Add tap water and carry out secondary remove impurity, pure rare earth solution stirring is added after having washed, add oxalic acid after constant temperature 20～40min the rare earth being partly dissolved out is precipitated, until in the middle of detection clear liquid without rare earth element time put into filter press and carry out filter press, filtrate processes to waste water, and filter cake is to oxidizing roasting；

(2) oxidizing roasting；After pretreatment filter cake addition sodium hydroxide solution out is uniformly mixed, carrying out roasting oxidation by kiln, controlling sintering temperature is 700～900 DEG C, is incubated complete to waste material roasting；

(3) acidolysis；Being added water by waste material after roasting in sour molten tank and make serosity, then add dissolving with hydrochloric acid, and add cosolvent hydrotropy, solution is filtrated to get rare earth chloride liquid, remove impurity through filter press；

(4) extraction；Utilize liquid caustic soda as extraction saponification agent, put into after liquid caustic soda in rare earth chloride liquid and remove impurity i.e. obtains rare-earth chloride solution, and reach waste water without ammonia, nitrogen discharged；

(5) precipitation；The rare-earth chloride solution obtained to step (4) slowly puts into pure rare earth feed liquid and oxalic acid, and temperature controls 60 DEG C～70 DEG C, utilizes reactor and sucking filtration pond to carry out rapid precipitation by precipitant and obtains rare earth oxalic acid thing；

(6) calcination；The rare earth oxalic acid thing utilizing kiln to obtain step (5) carries out 1000 DEG C of high temperature sinterings, then obtains high purity rare earth oxides through dehydration, carbonization, oxidation.