CN105755288B - A kind of method that zinc in discarded cathodic ray-tube fluorescent powder is reclaimed based on self-propagating reaction and rare earth is enriched with - Google Patents

Abstract

A kind of method for reclaiming the zinc in discarded cathodic ray-tube fluorescent powder based on self-propagating reaction and being enriched with rare earth, belongs to the recovery technology field of zinc.The method that the green reclaim of regenerating oxidation zinc discards zinc in cathodic ray-tube fluorescent powder is prepared using pretreatment zinc sulphide self-propagating reaction flooding zinc precipitation calcining.The discarded cathodic ray-tube fluorescent powder progress pretreatment obtained will be reclaimed except aluminium silicon, except the discarded cathodic ray-tube fluorescent powder after aluminium silicon is mixed with oxidant, be placed in high temperature resistant reaction vessel, trigger self-propagating reaction；Water-soluble reaction product is simultaneously stirred, and filter mixed liquor obtains leaching liquid containing zinc and rare-earth enrichment slag；Leaching liquid adjusts pH, and precipitation reclaims Zn (OH)₂；Calcine Zn (OH)₂ZnO powder is obtained, zinc comprehensive recovery is up to 98%.The present invention has simple for process, it is to avoid pernicious gas SO₂、H₂S generation；Valuable metal zinc is effectively reclaimed, while realizing the efficiently concentrating of rare earth resources.

Description

A self-propagating reaction-based recovery of zinc from waste cathode ray tube phosphors and enrichment The method of collecting rare earth

technical field

The invention relates to a method for recovering zinc from waste cathode ray tube fluorescent powder, in particular to a method for recycling zinc in waste cathode ray tube fluorescent powder by self-propagating reaction green and enriching rare earth, belonging to the technical field of zinc recovery.

Background technique

With the rapid development of display technology, cathode ray tube displays have entered a large number of scrapping stages. According to relevant statistics, in 2013 alone, more than 30 million CRT monitors were scrapped in my country. The average mass of fluorescent powder contained in each complete cathode ray tube screen glass is 1-7g, and the main components of waste cathode ray tube fluorescent powder are w(ZnS) 55-60%, w(Y ₂ O ₂ S:Eu) 25-30%, w(SiO ₂ ) 2-8%, w(Al) 2-5%, and a small amount of other trace impurity elements. Heavy metals such as zinc are usually acutely or chronically toxic. Incineration, landfilling or random discarding not only cause waste of resources, but also lead to soil or water pollution, causing great harm to animals and plants.

At present, the research on the recycling of waste cathode ray tube phosphor powder is still in its infancy. The existing research mainly focuses on the recovery of rare earth elements from cathode ray tube phosphor powder, and there is little talk about the recycling of zinc (patent application for invention patent 201210300550.6, 201210134477 .X). In the method of recycling cathode ray tube fluorescent powder proposed by Ma Lin (patent application 201110140164.0), dilute sulfuric acid is used to dissolve elements such as rare earth and zinc, and rare earth fluoride is recovered by filtration with hydrofluoric acid. At the same time, it is mentioned that aluminum, zinc, and cadmium can be obtained by adjusting the pH of the filtrate. However, this method does not propose a specific step for separating and recovering zinc. At the same time, a large amount of toxic gas H ₂ S is released during the leaching process, which leads to serious environmental pollution and safety problems, and increases the difficulty of waste gas treatment. Wang Qin pointed out in the patent (patent application 201110143325.1) that firstly the calcination oxidation treatment is carried out, the metal elements are leached out by adding acid, the rare earth is recovered by phosphate, and the zinc element is recovered by sodium carbonate precipitation. Although this method avoids the emission of H ₂ S, the calcination process A large amount of SO ₂ is produced, which also causes serious environmental pollution and safety problems, and increases the difficulty of waste gas treatment. Zhang Shengen proposed a method for removing glass slag and silicon-aluminum oxides in waste rare earth phosphors (patent application 201410022560.7), and proposed to use screening and hot alkali leaching process to remove coarse, medium and fine particles of glass slag and other silica in waste rare earth phosphors. Aluminum oxide impurities provide support for the pre-treatment process for this patent.

It can be seen that there are still many problems in the existing research on the recycling of phosphor powder from waste cathode ray tubes. First of all, the existing recovery process generally consumes a lot of energy, such as the calcination pretreatment process, and has strict requirements on equipment, such as alkali fusion and other steps; secondly, the recovery process inevitably causes sulfur pollution, such as the acid leaching process produces dangerous gases H ₂ S, and the calcination process inevitably produces a large amount of SO ₂ , which causes serious environmental and safety problems while high energy consumption; at the same time, the existing research focuses on the recovery and utilization of rare earth elements, and the main element Zn is also in the form of ions Into the solution together with rare earth elements, the recovery process not only caused the separation of rare earth ions and Zn ions, but also caused a lot of waste of zinc resources after recovery of rare earth ions.

The purpose of the present invention is mainly to solve the problem of zinc recovery in waste cathode ray tube fluorescent powder, not only to ensure the effective recovery of zinc valuable metals, but also to achieve effective enrichment of rare earth resources, while improving the economic value of recovery, to achieve a short process flow, Low energy consumption, less secondary pollution and other process advantages. Using the self-spreading method to recover zinc in waste cathode ray tube phosphors can effectively avoid the environmental, safety, energy consumption and other problems caused by the existing process. Self-spreading is a spontaneous reaction with fast reaction speed, low reaction energy consumption and stable products. A large amount of zinc resources can be recovered, the added value can be increased, and rare earth resources can be enriched at the same time, which greatly improves the efficiency of subsequent rare earth recovery compared with the existing technology.

Contents of the invention

The purpose of the present invention is mainly to solve the problem of zinc recovery in waste cathode ray tube fluorescent powder, not only to ensure the effective recovery of zinc valuable metals, but also to achieve effective enrichment of rare earth resources, while improving the economic value of recovery, to achieve a short process flow, Low energy consumption, less secondary pollution and other process advantages.

A method of reclaiming zinc in waste cathode ray tube fluorescent powder based on self-propagating reaction of the present invention is as follows:

Step 1: Pretreatment to remove aluminum and silicon

Perform primary screening on the recovered waste cathode ray tube fluorescent powder, and use hot alkaline solution to leach the fine glass slag, aluminum and other silicon-aluminum impurities;

Step 2: Self-propagating reaction

Finely grind the primary enrichment powder obtained after step one alkali leaching residue is dried, and oxidant (oxidant is one or a mixture of alkali metal peroxides or superoxides such as sodium peroxide and potassium peroxide) according to the mass ratio of 1 : 0.5～1:5 mixing, stirring evenly; put the mixed powder in a high temperature resistant reaction container to trigger a self-propagating reaction; in this step, through a self-propagating redox reaction, the zinc element in zinc sulfide is transformed into a soluble The zinc salt of the neutral solution, and the sulfur element is directly oxidized to form sulfate, which avoids the generation of toxic and harmful gases such as hydrogen sulfide and sulfur dioxide during acid leaching and high-temperature roasting, and greatly reduces the secondary pollution in the recycling process.

Step 3: Selective leaching of zinc

The cooled reaction product in step 2 is mixed and leached with deionized water at a solid-to-liquid ratio of 1:20 to 1:100 (g/mL). The aqueous solution is alkaline and is directly used for the leaching of Zn in the system. After the stirring is completed, filter. Rinse the precipitate with lye and water in sequence, add the washing liquid to the filtrate of this process to obtain a zinc-containing filtrate, collect the filter residue and dry it to obtain a rare earth enriched residue. In particular, the mass concentration of NaOH in the leaching solution during the leaching process can be adjusted to 2%-10% by adding NaOH to ensure that all ZnO is leached. Further, the leaching system is stirred at 20-80° C. for 0.5-4 hours.

Through the above steps 1 to 3, the mass content of rare earth elements in the rare earth enriched slag is increased from <10% initially to >60%.

Step 4: Recovery and preparation of zinc oxide

The zinc-containing filtrate in step 3 contains a high concentration of Zn(OH) ₄ ^2- , which is precipitated in the form of Zn(OH) ₂ by adding acid to adjust the pH, and the impurity elements Na ⁺ and SO ₄ ^2- remain in the filtrate, Calcination after filtration to prepare ZnO powder.

The self-propagating initiation method adopts one of methods such as chemical ignition, combustion wave ignition, local heating ignition, laser ignition, thermal explosion ignition or microwave ignition.

A green method for recovering zinc in waste cathode ray tube fluorescent powder by using pretreatment-zinc sulfide self-propagating reaction-water leaching to extract zinc-precipitation and calcination to prepare regenerated zinc oxide. The waste cathode ray tube fluorescent powder obtained by recycling is pretreated to remove aluminum and silicon, and the waste cathode ray tube fluorescent powder after aluminum and silicon removal is mixed with an oxidant, and placed in a high temperature resistant reaction container to initiate a self-propagating reaction; the reaction product is dissolved in water and stirred , filter the mixed solution to obtain zinc-containing leaching solution and rare earth enrichment slag; adjust the pH of the leaching solution, precipitate and recover Zn(OH) ₂ ; calcinate Zn(OH) ₂ to obtain ZnO powder, and the comprehensive recovery rate of zinc is as high as 98%. The invention has the advantages of simple and easy process, and the raw materials and equipment used are relatively common and cheap; the energy consumption is extremely low and the internal recycling can be realized; the environmental protection can avoid the generation of harmful gases SO ₂ and H ₂ S; the valuable metal zinc can be recovered effectively, At the same time, the efficient enrichment of rare earth resources is realized.

The invention has the advantages of simple and easy process, common and cheap raw materials and equipment, extremely low energy consumption, internal recycling, and efficient enrichment of rare earth resources while recovering the valuable metal zinc.

Description of drawings

Fig. 1 shows a flow chart of a method for recovering zinc in waste cathode ray tube phosphors and enriching rare earths based on self-propagating reaction.

detailed description

The present invention is described below in conjunction with the examples, but the present invention is not limited to the following examples.

Example 1

Primary screening is carried out on the waste cathode ray tube fluorescent powder obtained from recovery, and the fine glass slag, aluminum and other silicon-aluminum impurities are leached with hot alkali solution. After removing aluminum and silicon, the waste cathode ray tube fluorescent powder is mixed with sodium peroxide at a mass ratio of 1:0.5, placed in a high-temperature resistant reaction vessel, and dripping water triggers a self-propagating reaction; water-soluble at a solid-to-liquid ratio of 1:20 (g/mL) For the reaction product, add 10g of sodium hydroxide solid, stir at 75°C for 4 hours, filter the mixed solution to obtain zinc-containing leaching solution and rare earth enrichment slag; adjust the pH of the leaching solution, and recover Zn(OH) ₂ by precipitation; calcining Zn(OH) ) ₂ to obtain ZnO powder, the recovery rate of zinc is 98.3%.

Example 2

Primary screening is carried out on the waste cathode ray tube fluorescent powder obtained from recovery, and the fine glass slag, aluminum and other silicon-aluminum impurities are leached with hot alkali solution. The discarded cathode ray tube fluorescent powder after removing aluminum and silicon is mixed with sodium peroxide at a mass ratio of 1:1, placed in a high-temperature resistant reaction vessel, and dripped with alcohol to initiate a self-propagating reaction; at a solid-to-liquid ratio of 1:35 (g/mL) For the water-soluble reaction product, add 5g of sodium hydroxide solid, stir at 80°C for 2.5 hours, filter the mixed solution to obtain zinc-containing leaching solution and rare earth enrichment slag; adjust the pH of the leaching solution, and recover Zn(OH) ₂ by precipitation; calcining Zn (OH) ₂ to obtain ZnO powder, the recovery rate of zinc is 98.6%.

Example 3

Primary screening is carried out on the waste cathode ray tube fluorescent powder obtained from recovery, and the fine glass slag, aluminum and other silicon-aluminum impurities are leached with hot alkali solution. The discarded cathode ray tube fluorescent powder after removing aluminum and silicon is mixed with sodium peroxide at a mass ratio of 1:2, placed in a high-temperature resistant reaction vessel, and tungsten wire is ignited to initiate a self-propagating reaction; according to a solid-liquid ratio of 1:40 (g/mL ) water-soluble reaction product, add 7.5g sodium hydroxide solid, after stirring at 20°C for 3.5h, filter the mixed solution to obtain zinc-containing leaching solution and rare earth enrichment slag; the leaching solution adjusts pH, and precipitation recovers Zn(OH) ₂ ; Calcining Zn(OH) ₂ to obtain ZnO powder, the recovery rate of zinc is 99.1%.

Example 4

Primary screening is carried out on the waste cathode ray tube fluorescent powder obtained from recovery, and the fine glass slag, aluminum and other silicon-aluminum impurities are leached with hot alkali solution. The discarded cathode ray tube fluorescent powder after removing aluminum and silicon is mixed with sodium peroxide in a mass ratio of 1:3, placed in a high-temperature resistant reaction vessel, and the nickel alloy coil is ignited to cause a self-propagating reaction; according to a solid-to-liquid ratio of 1:45 (g /mL) water-soluble reaction product, add 3g sodium hydroxide solid, after stirring at 35°C for 3h, filter the mixed solution to obtain zinc-containing leaching solution and rare earth enrichment slag; the leaching solution adjusts pH, and precipitation recovers Zn(OH) ₂ ; Calcining Zn(OH) ₂ to obtain ZnO powder, the recovery rate of zinc is 97.9%.

Example 5

Primary screening is carried out on the waste cathode ray tube fluorescent powder obtained from recovery, and the fine glass slag, aluminum and other silicon-aluminum impurities are leached with hot alkali solution. The discarded cathode ray tube fluorescent powder after removing aluminum and silicon is mixed with sodium peroxide at a mass ratio of 1:4, placed in a high-temperature resistant reaction vessel, and locally heated by a laser triggers a self-propagating reaction; according to a solid-liquid ratio of 1:65 (g/mL ) water-soluble reaction product, add 4g of sodium hydroxide solid, and after stirring at 45°C for 2 hours, filter the mixed solution to obtain zinc-containing leaching solution and rare earth enrichment slag; adjust the pH of the leaching solution, and recover Zn(OH) ₂ by precipitation; calcining Zn (OH) ₂ to obtain ZnO powder, the recovery rate of zinc is 98.5%.

Example 6

Primary screening is carried out on the waste cathode ray tube fluorescent powder obtained from recovery, and the fine glass slag, aluminum and other silicon-aluminum impurities are leached with hot alkali solution. The waste cathode ray tube fluorescent powder after removing aluminum and silicon is mixed with sodium peroxide at a mass ratio of 1:5, placed in a high temperature resistant reaction vessel, and heated by an electric heating plate to cause a self-propagating reaction; according to a solid-liquid ratio of 1:80 (g/mL ) water-soluble reaction product, add 6g of sodium hydroxide solid, after stirring at 50°C for 1.5h, filter the mixed solution to obtain zinc-containing leaching solution and rare earth enrichment slag; adjust the pH of the leaching solution, and recover Zn(OH) ₂ by precipitation; calcining Zn(OH) ₂ obtains ZnO powder, and the recovery rate of zinc is 99.3%.

Example 7

Primary screening is carried out on the waste cathode ray tube fluorescent powder obtained from recovery, and the fine glass slag, aluminum and other silicon-aluminum impurities are leached with hot alkali solution. The discarded cathode ray tube fluorescent powder after removing aluminum and silicon is mixed with sodium peroxide at a mass ratio of 1:4.5, placed in a high-temperature resistant reaction vessel, and heated by microwaves to cause a self-propagating reaction; water-soluble reaction product at a solid-to-liquid ratio of 1:90, replenished Add 8g of sodium hydroxide solid, stir at 60°C for 1 hour, filter the mixed solution to obtain zinc-containing leaching solution and rare earth enrichment slag; adjust the pH of the leaching solution, precipitate and recover Zn(OH) ₂ ; calcinate Zn(OH) ₂ to obtain ZnO powder, the recovery rate of zinc is 98.5%.

Example 8

Primary screening is carried out on the waste cathode ray tube fluorescent powder obtained from recovery, and the fine glass slag, aluminum and other silicon-aluminum impurities are leached with hot alkali solution. The discarded cathode ray tube fluorescent powder after removing aluminum and silicon is mixed with sodium peroxide at a mass ratio of 1:5, placed in a high temperature resistant reaction vessel, and thermal detonation is ignited to trigger a self-propagating reaction; according to a solid-liquid ratio of 1:100 (g/mL ) water-soluble reaction product, after stirring at 65°C for 0.5h, filter the mixed solution to obtain zinc-containing leaching solution and rare earth enrichment slag; adjust the pH of the leaching solution, precipitate and recover Zn(OH) ₂ ; calcinate Zn(OH) ₂ to obtain ZnO powder , The recovery rate of zinc is 98.3%.

Claims (7)

1. a kind of method that zinc in discarded cathodic ray-tube fluorescent powder is reclaimed based on self-propagating reaction and rare earth is enriched with, its feature It is, comprises the following steps：

Step one：Pretreatment removes aluminium silicon

The primary screening of discarded cathodic ray-tube fluorescent powder progress obtained will be reclaimed, thin glass dregs therein are leached using heat alkali liquid With aluminium and other sial impurity；

Step 2：Self-propagating reaction

The primary enrichment powder fine grinding obtained after step one alkali phase analysis is dried is mixed with oxidant, is stirred；Mixed powder is put In high temperature resistant reaction vessel, trigger self-propagating reaction；In this step, by self- propagating redox reaction, in zinc sulphide Zn-ef ficiency is converted into the zinc salt for dissolving in alkaline solution, and element sulphur is directly oxidized generation sulfate；Oxidant is alkali metal One or more of mixture in peroxide or superoxides；

Step 3：Selectivity leaching zinc

Reaction product after step 2 cooling presses solid-to-liquid ratio 1 with deionized water:20~1:100g/mL mixing leaches, and the aqueous solution is in Alkalescence, is directly used in the leaching of Zn in system, and stirring is filtered after terminating, and rinses precipitation successively with alkali lye and water, washing lotion is incorporated to this The filtrate of process, obtains and acquisition rare-earth enrichment slag is dried after filtrate containing zinc, residue collection；Leached by adding NaOH regulations Journey；

Step 4：Recovery prepares zinc oxide

Zn (OH) in filtrate containing zinc in step 3 containing high concentration₄ ^2-, by adding acid for adjusting pH to make it with Zn (OH)₂Form is sunk Form sediment, impurity element Na⁺And SO₄ ^2-Stay in filtrate, calcining prepares ZnO powder after filtering.

2. according to a kind of zinc and richness reclaimed based on self-propagating reaction in discarded cathodic ray-tube fluorescent powder described in claim 1 Collect the method for rare earth, it is characterised in that step 2 oxidant is one kind or mixture in sodium peroxide, potassium peroxide.

3. according to a kind of zinc and richness reclaimed based on self-propagating reaction in discarded cathodic ray-tube fluorescent powder described in claim 1 Collect the method for rare earth, it is characterised in that step 3 adjusts NaOH mass concentrations in leaching process, infusion solution by adding NaOH 2%~10%, to ensure Zn all leachings.

4. according to a kind of zinc and richness reclaimed based on self-propagating reaction in discarded cathodic ray-tube fluorescent powder described in claim 1 Collect the method for rare earth, it is characterised in that step 3 leaching system is stirred at 20~80 DEG C, mixing time 0.5~ 4h。

5. according to a kind of zinc and richness reclaimed based on self-propagating reaction in discarded cathodic ray-tube fluorescent powder described in claim 1 Collect the method for rare earth, it is characterised in that arrive step 3 process by above step one, rare-earth enrichment slag rare earth elements quality contains Amount brings up to ＞ 60% by initial ＜ 10%.

6. according to a kind of zinc and richness reclaimed based on self-propagating reaction in discarded cathodic ray-tube fluorescent powder described in claim 1 Collect the method for rare earth, it is characterised in that self- propagating initiation method is lighted a fire using chemic ignition, combustion wave igniting, local heating, swashed One kind in the quick-fried igniting of luminous point pry- or microwave ignition method.

7. according to a kind of zinc and richness reclaimed based on self-propagating reaction in discarded cathodic ray-tube fluorescent powder described in claim 1 Collect the method for rare earth, it is characterised in that primary enrichment powder fine grinding is with oxidant according to mass ratio 1:0.5~1:5 mixing.