CN1396119A

CN1396119A - Process for comprehensive utilization of waste acid containing titanium oxide

Info

Publication number: CN1396119A
Application number: CN 02133388
Authority: CN
Inventors: 何章亮; 曾冬梅; 张小霞; 刘凌; 那丽
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2002-07-01
Filing date: 2002-07-01
Publication date: 2003-02-12
Anticipated expiration: 2022-07-01
Also published as: CN1176024C

Abstract

A comprehensive utilization method of titanium dioxide waste acid, which completely combines the comprehensive utilization of titanium dioxide waste acid with zinc hydrometallurgy technology, effectively solves the technical problem that titanium dioxide waste acid is difficult to handle and difficult to fully recover. The specific technical plan is: heat and hydrolyze the waste titanium dioxide acid, and return the metatitanic acid obtained from the hydrolysis to the main process of titanium dioxide production or use it to prepare titanium yellow powder; use the filtrate obtained from hydrolysis and zinc-containing oxides as raw materials, and adopt hydrometallurgical process Prepare active zinc oxide, basic zinc carbonate, ferric oxide and zinc-containing ammonium sulfate. Since the entire process is basically a wet closed-circuit cycle, it can comprehensively utilize titanium dioxide waste acid to prepare high-quality, high-value-added products without polluting the environment.

Description

Comprehensive utilization method of titanium white waste acid

One, the technical field

The invention relates to a method for treating waste acid generated in titanium dioxide production by a sulfuric acid method.

Second, background Art

The production methods of titanium dioxide (titanium dioxide) mainly include two methods: the chlorination process and the sulfuric acid process are mainly adopted in China due to the limitation of raw materials. The biggest problem of the sulfuric acid method is that 5-7 tons of waste sulfuric acid with the concentration of about 20 percent and a large amount of dilute acid are generated when one ton of titanium dioxide is produced, so that the treatment of the waste acid is a key problem which needs to be solved when the sulfuric acid method is used for preparing the titanium dioxide.

Regarding the treatment of titanium white waste acid, titanium white manufacturers in China have various modes: the method comprises the steps of neutralization discharge, production of salts such as potassium sulfate, ammonium sulfate, magnesium sulfate and the like, concentration and reuse and the like, but the method is not a satisfactory method, and is not large in investment and small in output, namely, one pollution is converted into the other pollution. Japan Shiyuan company has proposed a "stone method", namely produce the artificial rutile with the waste acid produced by sulfate process titanium dioxide production; the Beijing color metals research institute is also working on the research of preparing synthetic rutile from titanium white waste acid (see "Sichuan non-ferrous metals", No. 3 of 2001, P65), but there is a problem of treating waste acid containing high concentration of iron in view of the present disclosure.

Third, the invention

The invention provides a comprehensive utilization method for treating waste acid generated in titanium dioxide production by a sulfuric acid method aiming at the problems in the prior art, the process flow of the method is basically closed cycle by a full wet method, the technology is mature, the equipment is conventional, and no pollution is caused; can comprehensively recover acid, titanium and iron in the titanium white waste acid and prepare various products with high quality and added value and large market demand.

The technical scheme of the invention is as follows: and (3) treating titanium white waste acid by using a zinc hydrometallurgy process. Firstly, titanium white waste acid is heated and hydrolyzed, metatitanic acid obtained by hydrolysis returns to the main process of titanium white production or is used for preparing titanium yellow powder, and zinc-containing oxide raw materials are leached from filtrate obtained by hydrolysis and are used for preparing active zinc oxide, ferric oxide and zinc-containing ammonium sulfate.

1. The chemical reaction formula of the titanium white waste acid by heating hydrolysis is as follows: the process conditions are as follows: adding the variety, completing the reaction under stirring, boiling the temperature, controlling the time to limit the completion of the hydrolysis reaction,generally 1.5 to 2.5 hours. Filtering the metatitanic acid precipitate obtained by hydrolysis, washing with acidified water until no iron is detected, and washing with pure water. If the physical and chemical properties of the titanium dioxide are the same as those of the main process of titanium dioxide production, the titanium dioxide can return to the main process; if the physical and chemical properties are different from the main flow of titanium white production or titanium yellow powder needs to be prepared, the titanium yellow powder is used as a raw material for preparing the titanium yellow powder.

2. Preparation of titanium yellow powder from metatitanic acid

The process steps of preparing the titanium yellow powder by the metatitanic acid sequentially comprise drying, calcining and crushing; the drying and calcining is to obtain titanium yellow by drying and calcining a metatitanic acid filter cake obtained by filtering and washing, wherein the thermal decomposition chemical reaction formula of the metatitanic acid during calcining is as follows: the calcination temperature is 650-850 ℃, and the calcination time is 2-3 hours; the grinding is to prepare the titanium yellow into a powdery finished product.

3. Preparation of active zinc oxide from filtrate

The process steps of preparing the active zinc oxide from the filtrate sequentially comprise leaching, neutralizing, filtering and washing, precipitating alum, filtering and washing, secondary oxidation, filtering and washing, replacement, filtering and washing, precipitating ammonium, filtering and washing, drying, calcining and crushing. The leaching is to add zinc-containing oxide into the filtrate so as to make full use of a large amount of sulfuric acid contained in the filtrate. The main chemical reactions of the leaching process are as follows:

the accompanying side reactions are:

the leaching process conditions are as follows: and (3) completing the reaction under stirring, controlling the temperature to be 80-90 ℃, controlling the end point pH to be 1.5-1.8, and controlling the time to be 1-2 hours. And the neutralization is to add a neutralizing agent into the mixed liquid formed in the leaching process, and the end point pH is controlled to be 5-5.4, so that the impurity removal of the mixed liquid formed in the leaching process is facilitated. The alum deposition is that ammonium persulfate is added into the filtrate after primary impurity removal (Pb, In, Ge, etc.) by filtration and washing to ensure that Fe²⁺Oxidation to Fe³⁺And producing ammonioiarosite, thus purifying the raw material for preparing the active zinc oxide and obtaining the raw material for preparing the ferric oxide. Oxidation of Fe by ammonium persulphate²⁺Is Fe³⁺The reaction formula (c) is as follows:

the adding amount of ammonium persulfate is Fe in the oxidizing solution²⁺90-100% of the required theoretical amount.

The generation reaction of the ammonium jarosite is as follows:

the process conditions for precipitating alum are as follows: adding seed crystals, completing the reaction at the temperature of 90-boiling for 1-4 hours under stirring, adding a neutralizing agent to keep the pH of the reaction liquid at 1.5-2, precipitating alum, and finally adjusting the pH of the reaction liquid to 4-4.5 for half an hour. The secondary oxidation is to add potassium permanganate solution into the filtrate of the ammonioiarosite filtration to remove Mn by oxidation²⁺And Fe²⁺The main chemical reaction is as follows:

the process conditions of the secondary oxidation are as follows: the reaction is completed under stirring, the temperature is 60-70 ℃, the time is 40 minutes-1 hour, and the end point pH is controlled to be 4-4.5. The replacement is to add zinc powder into the filtrate for filtering manganese slag and iron slag to further purify the solution, and the main chemical reaction is as follows:

the process conditions of the replacement are as follows: the reaction is completed under stirring, the adding amount of the zinc powder is 1.5-2 times of the theoretical amount, the temperature is controlled to be 60-80 ℃, the final pH value of the solution is 5-5.4, and the time is 1.5-2 hours. Ammonium precipitation is to add ammonium carbonate saturated liquid into the filtrate of which the replacement slag is filtered off to obtain basic zinc carbonate, and the reaction formula is as follows:

the process conditions of ammonium precipitation are as follows: the reaction temperature is 40-50 ℃, the end point pH is controlled at 6.8-7.0, the temperature is raised to 70-75 ℃ and stirred for 1 hour, and finally the heat preservation and precipitation are carried out for 3-4 hours at 60 ℃. Drying is to dry the basic zinc carbonate filter cake obtained by filtering and washing to ensure that the water content is less than 2.5 percent, and calcining is to thermally decompose the basic zinc carbonate to obtain the active zinc oxide, wherein the reaction formula is as follows:

the calcination temperature is 450-500 ℃, and the calcination time is 2-3 hours. The crushing is to prepare the blocky active zinc oxide into a finished product.

4. Preparation of iron sesquioxide

The ferric oxide is prepared by taking ammoniojarosite obtained in the alum precipitation process as a raw material, and the process steps sequentially comprise drying, calcining and crushing, wherein the calcining temperature is 700-950 ℃, and the calcining time is 2-2.5 hours. The thermal decomposition reaction formula during calcination is as follows:

SO produced by calcination₃And SO₂Can be absorbed by ammonium carbonate solution to generate ammonium sulfate solution for preparing zinc-containing ammonium sulfate.

5. Preparation of zinc-containing ammonium sulfate

The preparation of the zinc-containing ammonium sulfate takes the filtrate generated by filtering and washing basic zinc carbonate and the solution formed by absorbing sulfur trioxide and sulfur dioxide generated by calcining ammonioiarosite by ammonium bicarbonate as raw materials, and the process steps are concentration, cooling crystallization and drying in sequence.

Besides the comprehensive utilization scheme, part of the basic zinc carbonate obtained in the ammonium precipitation step can be used for preparing active zinc oxide after being filtered, washed and dried, and part of the basic zinc carbonate can be used for preparing a finished product of the basic zinc carbonate. If the basic zinc carbonate finished product is prepared, the dried basic zinc carbonate is crushed according to the requirement.

In order to minimize environmental pollution, ammonium carbonate solution formed by absorbing carbon dioxide generated by calcining basic zinc carbonate with ammonia water can be used as a supplementary raw material for the ammonium precipitation process.

In the comprehensive utilization scheme, the seed crystal used in the heating hydrolysis process is prepared from ammonia water and titanium dioxide waste acid, and the addition amount of the seed crystal is 1-1.5% of the amount of titanium dioxide (converted) contained in the titanium dioxide waste acid; the zinc-containing oxide added in the leaching process is zinc calcine or zinc smoke dust or hot galvanizing ash subjected to calcination andalkaline leaching treatment; the neutralizing agent added in the neutralization step is ammonia water or the combination of ammonia water and any one of zinc calcine, zinc smoke dust, hot-dip galvanizing ash and calcium carbonate powder; the seed crystal added in the alum precipitation procedure is ammoniojarosite, and the neutralizer is ammonia water and/or basic zinc carbonate.

The invention has the following beneficial effects:

1. the provided method can comprehensively recover useful substances in the titanium white waste acid and prepare the useful substances into titanium yellow powder, active zinc oxide, ferric oxide, basic zinc carbonate and a zinc-containing ammonium sulfate compound fertilizer, and the product has the advantages of low cost, high quality and strong market competitive advantage.

2. The whole process flow is basically closed-loop circulation of a full wet method, and the problem of environmental pollution in the treatment of titanium white waste acid is effectively solved.

3. The zinc hydrometallurgy technology is mature, the equipment is conventional, and the industrial production is easy to realize.

Description of the drawings

FIG. 1 is a process flow diagram of the comprehensive utilization of titanium dioxide waste acid proposed by the present invention;

FIG. 2 is another process flow diagram of the comprehensive utilization method of titanium dioxide waste acid.

Fifth, detailed description of the invention

Example 1:

the process flow of the comprehensive utilization method of titanium white waste acid in the embodiment is shown in fig. 1, the titanium white waste acid is heated and hydrolyzed, metatitanic acid obtained by hydrolysis is used for preparing titanium yellow powder, and filtrate obtained by hydrolysis is used for preparing active zinc oxide and iron oxide red (Fe)₂O₃) And zinc-containing ammonium sulfate.

(1) Heating hydrolysis of titanium white waste acid

The components and the contents (weight percentage) of the components of the titanium white waste acid are as follows:

H₂SO₄20.3 Fe 2.4

Mg 0.5 Ca 0.0037

TiO₂9.51 V 0.0009

Co 0.00095

the equipment is provided with heating and temperature control,A condensation reflux device and a reaction kettle of a stirrer. The process conditions are as follows: adding 1% of seed crystal (weight percentage) according to TiO₂Calculating the content, wherein the seed crystal is prepared from ammonia water and titanium dioxide waste acid, and the adding amount of the ammonia water is limited by the fact that the terminal pH of the obtained titanium dioxide waste acid reaches 2-4; boiling at the temperature; the stirring speed is 120 r/min; the time is 2 hours.

(2) Preparing titanium yellow powder

Filtering metatitanic acid precipitate obtained by hydrolysis, washing with sulfuric acid acidified water with pH of 1.5 until no iron is detected, washing with pure water to obtain metatitanic acid filter cake, drying the filter cake at 110 deg.C, calcining at 650 deg.C, 800 deg.C, 850 deg.C for 2 hr, and pulverizing to obtain titanium yellow powder. TiO thereof₂The contents are 93.6%, 98.07% and 99.26% (weight percentage) respectively, and the indexes of GB1706-93 and ZGB13004-90 of national standard and ministry of China are achieved.

(3) Preparation of activated Zinc oxide

Leaching, neutralizing, filtering and washing, precipitating alum, filtering and washing, secondary oxidizing, filtering and washing, replacing, filtering and washing, precipitating ammonium, filtering and washing, drying, calcining and crushing the filtrate obtained by hydrolysis to obtain the finished product of the active zinc oxide. Each of the above filtration and washing steps was washed with acidified water of sulfuric acid having a pH of 5. Zinc-containing oxidation added in leaching processThe material is a mixture of zinc flue powder and dust collecting white powder, and the composition (weight percentage) of the material is as follows:

name (R)	Zinc flue powder						Dust collecting white powder	Mixture material (actual measurement value)
name (R)	Zinc flue powder						Dust collecting white powder	Mixture material (actual measurement value)	Proportioning	30％						70％
Composition of	ZnO	Ge	In	Pb	Cl	Co	ZnO	ZnO	Proportioning	30％						70％
Composition of	ZnO	Ge	In	Pb	Cl	Co	ZnO	ZnO	Content (%)	55	0.02-0.04	0.3	8-10	0.4	Micro-scale	80	73.114

The process conditions and process parameters are as follows: zinc-containing oxide and titanium dioxide waste acid hydrolysis filtrate are 1: 7 (weight ratio); the temperature is 85 ℃; the time is 1 hour; the stirring speed is 120 r/min; the end point pH was 1.8.

The neutralizing agent added in the neutralization process is ammonia water and hot-dip galvanizing ash fine powder, and the final pH value is controlled to be 5.2.

The process conditions of the alum deposition procedure are as follows: the temperature is 95 ℃; zn²⁺103.9 g/l; sigma Fe 23.8 g/l; the adding amount of ammonium persulfate is 95 percent of the theoretical amount; the seed crystal is ammonium jarosite, and the addition amount is 150 g/L; controlling the pH value of the precipitated alum to be 1.8; the stirring speed is 120 r/min; the time is 4 hours; neutralizing agent basic zinc carbonate, and adjusting pH to 4 after 3.5 hours of alum precipitation.

The process conditions of the secondary oxidation process are as follows: the temperature is 60 ℃; the stirring speed is 120 r/min; oxidizing with 0.5% potassium permanganate solution for 1 hr, and controlling the pH value at the end point of the solution to 4.5.

The process conditions of the replacement procedure are as follows: the temperature is 60 ℃; the dosage of the zinc powder is 2 times of the theoretical quantity; the stirring speed is 120 r/min; the end point of the solution is pH5.4; the time is 1.5 hours.

The process conditions of the ammonium precipitation procedure are as follows: the ammonium precipitation temperature is 40 ℃; end point pH7.0; the adding amount of the ammonium bicarbonate saturated solution is limited by the pH value of the end point of the reaction solution reaching 7.0; when the pH of the reaction solution reaches 7.0, the temperature is raised to 70 ℃, the reaction solution is stirred for 1 hour, and finally the reaction solution is subjected to heat preservation and precipitation for 4 hours at the temperature of 60 ℃.

The drying temperature in the drying step was 105 ℃.

The calcination temperature in the calcination step was 500 ℃ and the calcination time was 2 hours. The active zinc oxide prepared by the embodiment reaches the index of national ministry standard HG/T2572-94.

(4) Preparation of iron Red (Fe)₂O₃)

Filtering and washing ammoniojarosite obtained in the alum precipitation step to form a filter cake, drying the filter cake at 110 ℃, calcining the filter cake at 700 ℃, 750 ℃, 800 ℃ and 850 ℃ for 2 hours, and crushing the filter cake to obtain Fe₂O₃The contents are 85.45%, 95.96%, 96.15% and 98.2% respectively, and all reach the indexes of national standard GB1863-89 and ministerial standard HG/T2574-94.

(5) Preparation of zinc-containing ammonium sulfate

And (3) concentrating, cooling, crystallizing and drying a solution formed by absorbing the filtrate generated by filtering and washing basic zinc carbonate and sulfur trioxide generated by calcining ammonioiarosite by using ammonium bicarbonate solution to obtain the zinc-containing ammonium sulfate. The ammonium sulfate prepared in this example contained 17.26% N, 1.52% ZnH, and a small amount of NH₄Cl、MgCl₂And MgSO₄。

The amount of each product prepared in this example calculated for treating 1 ton of titanium dioxide waste acid was: 89kg of titanium yellow powder, 128kg of active zinc oxide and iron oxide red (Fe)₂O₃)35kg, zinc-containing ammonium sulfate 200 kg.

Example 2:

the process flow of the comprehensive utilization method of titanium dioxide waste acid in the embodiment is shown in fig. 2, the titanium dioxide waste acid is heated and hydrolyzed, metatitanic acid obtained by hydrolysis returns to the main flow of titanium dioxide production, and filtrate obtained by hydrolysis is used for preparing active zinc oxide, basic zinc carbonate and iron oxide red (Fe)₂O₃) And zinc-containing ammonium sulfate.

The present embodiment differs from embodiment 1 as follows:

(1) the metatitanic acid obtained by hydrolysis returns to the main flow of titanium dioxide production.

(2) The zinc-containing oxide added in the leaching process for preparing the basic zinc carbonate and the active zinc oxide is prepared by calcining hot galvanizing ash containing 77 percent of zinc and alkaline leaching. The calcination process conditions are as follows: the calcining temperature is 500 ℃, and the calcining time is 2 hours. The process conditions of alkaline leaching are as follows: calcined Zinc Ash: 2% (NaOH + Na)₂CO₃) Liquid is 1: 1 (weight ratio); the temperature is normal temperature; the time period was 6 hours. And (5) after the alkaline leaching is finished, filtering and washing for later use.

(3) Filtering, washing and drying the basic zinc carbonate obtained in the ammonium precipitation step, wherein the half of the basic zinc carbonate is used for preparing an active zinc oxide finished product, and the half of the basic zinc carbonate is directly crushed into the basic zinc carbonate finished product.

(4) And absorbing carbon dioxide generated by calcining the basic zinc carbonate filter cake with ammonia water to form ammonium bicarbonate solution as a supplementary raw material for the ammonium precipitation process.

(5) The neutralizing agents used in the neutralization step of this example were ammonia and calcium carbonate powders.

The amount of each product prepared in this example calculated for treating 1 ton of titanium dioxide waste acid was: 62kg of active zinc oxide, 91kg of basic zinc carbonate and iron oxide red (Fe)₂O₃)34kg, zinc-containing ammonium sulfate 202 kg.

Claims

1, a kind of comprehensive utilization method of titanium white waste acid, it is characterized in that:

(1) Heat and hydrolyze the waste titanium dioxide acid, the metatitanic acid obtained from hydrolysis is returned to the main process of titanium dioxide production or used to prepare titanium yellow powder, and the filtrate obtained from hydrolysis is leached from zinc-containing oxide materials to prepare active zinc oxide, ferric oxide and zinc-containing sulfuric acid ammonium,

(2) Heating and hydrolysis of titanium white waste acid should be added with crystal seeds and completed under stirring. The temperature control is to make the titanium white waste acid boil, and the time control is limited to the completion of the hydrolysis reaction.

(3) The process steps of preparing titanium yellow powder from metatitanic acid are drying, calcination and crushing in sequence. Drying and calcination is to dry the metatitanic acid filter cake obtained by filtering and washing and then calcining to obtain titanium yellow. The temperature of calcination is 650-850 ℃, the calcination time is 2 to 3 hours, and the pulverization is to prepare titanium yellow into a powdery finished product.

(4) The process steps of preparing active zinc oxide from the filtrate are leaching, neutralization, filter washing, alum sinking, filter washing, secondary oxidation, filter washing, replacement, filter washing, ammonium precipitation, filter washing, drying, calcination, pulverization , leaching is to add zinc-containing oxides to the filtrate and complete the chemical reaction under stirring. The temperature is controlled at 80-90°C, the pH at the end is controlled at 1.5-1.8, and the time is 1-2 hours. Neutralization is formed in the leaching process. A neutralizing agent is added to the mixed solution, and the pH at the end point is controlled at 5 to 5.4. For sinking alum, ammonium persulfate is added to the filtrate after filtering and washing for preliminary impurity removal, so that Fe ²⁺ is oxidized to Fe ³⁺ , and jarosite is formed. The amount of ammonium persulfate added is 90-100% of the theoretical amount required for Fe ²⁺ in the oxidation solution. The reaction is completed by adding seeds and stirring. The temperature is controlled at 90°C to boiling, and the time is 1-4 hours. Keep the pH of the reaction solution at 1.5-2, and adjust the reaction solution to pH 4-4.5 in the last half an hour of sinking alum. The second oxidation is to add potassium permanganate solution to the filtrate of jarosite to oxidize and remove Mn ²⁺ and Fe ²⁺ , the reaction is completed under stirring, the temperature is controlled at 60-70°C, the time is 40 minutes to 1 hour, and the pH at the end is controlled at 4-4.5. The replacement is to add zinc powder to the filtrate that removes manganese slag and iron slag to purify solution, the reaction is completed under stirring, the amount of zinc powder added is 1.5 to 2 times the theoretical amount, the temperature is controlled at 60 to 80 °C, the pH of the solution end point is 5 to 5.4, and the time is 1.5 to 2 hours. The ammonium precipitation is to filter out the replacement residue Add saturated solution of ammonium bicarbonate to the filtrate, the reaction temperature is 40-50°C, the final pH is controlled at 6.8-7.0, then the temperature is raised to 70-75°C and stirred for 1 hour, and finally the base is obtained by heat preservation and precipitation at 60°C for 3-4 hours Formula zinc carbonate, drying is to dry the basic zinc carbonate filter cake obtained by filtering and washing, and calcination is to thermally decompose basic zinc carbonate to obtain active zinc oxide, the calcination temperature is 450-500 ℃, and the calcination time is 2-3 hours , crushing is to prepare the block active zinc oxide as a finished product,

(5) Ferric oxide is calcined after drying the jarosite filter cake. The calcining temperature is 700-950° C., and the calcining time is 2-2.5 hours. The block-shaped ferric oxide obtained by calcining is pulverized into a finished product.

(6) Zinc-containing ammonium sulfate is made by concentrating the solution formed by filtering and washing the filtrate produced by basic zinc carbonate and calcining jarosite and sulfur dioxide after being absorbed by ammonium bicarbonate solution, cooling and crystallizing, and drying.

2. The comprehensive utilization method of titanium dioxide waste acid according to claim 1, characterized in that the dried basic zinc carbonate filter cake becomes the finished product of basic zinc carbonate after crushing.

3. The comprehensive utilization method of titanium white waste acid according to claim 1 or 2, characterized in that the carbon dioxide produced by calcining basic zinc carbonate is absorbed by ammonia water to form ammonium bicarbonate liquid as a supplementary raw material for the ammonium precipitation process.

4. The method for comprehensive utilization of titanium white waste acid according to claim 1 or 2, characterized in that the seed crystals used in the heating hydrolysis process are prepared from ammonia water and titanium white waste acid, and the amount of seed crystals added is 1-1.5% of the amount of titanium dioxide contained.

5. The comprehensive utilization method of titanium white waste acid according to claim 3, characterized in that the used crystal seed in the heating hydrolysis process is prepared from ammonia water and titanium white waste acid, and the amount of the seed crystal added is the amount contained in the titanium white waste acid. 1-1.5% of the amount of titanium dioxide.

6. The comprehensive utilization method of titanium white waste acid according to claim 1 or 2, characterized in that the zinc-containing oxide added in the leaching process is zinc calcine or zinc fume or hot-dip galvanized ash after calcination and alkali leaching .

7. The comprehensive utilization method of titanium white waste acid according to claim 1 or 2, characterized in that the neutralizing agent added in the neutralization process is ammonia water or ammonia water and zinc calcine, zinc fume, hot-dip galvanizing ash, calcium carbonate A combination of any of the powders.

8. The comprehensive utilization method of titanium white waste acid according to claim 1 or 2, characterized in that the seed crystal added in the alum sinking process is jarosite, and the neutralizing agent is ammonia water and/or basic zinc carbonate.