CN1706752A - Hydrochloric acid process for treating, regenerating and reusing waste TiO2 liquid - Google Patents
Hydrochloric acid process for treating, regenerating and reusing waste TiO2 liquid Download PDFInfo
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- CN1706752A CN1706752A CN 200410022777 CN200410022777A CN1706752A CN 1706752 A CN1706752 A CN 1706752A CN 200410022777 CN200410022777 CN 200410022777 CN 200410022777 A CN200410022777 A CN 200410022777A CN 1706752 A CN1706752 A CN 1706752A
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- ferrous sulfate
- hydrochloric acid
- titanium dioxide
- waste liquid
- hydrogen chloride
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Abstract
The hydrochloric acid process for treating, regenerating and reusing waste TiO2 liquid includes the following steps: compounding material with waste TiO2 liquid and concentrated sulfuric acid in the weight ratio of 1 to0.10-0.25; heating to fractionation the material to produce HCl gas and supersaturated ferrous sulfate solution; absorbing HCl gas with dilute hydrochloric acid in falling film graphite absorber to produce concentrated hydrochloric acid for TiO2 production; crystallizing supersaturated ferrous sulfate solution from the externally heated graphite evaporator through natural cooling in crystallizer; centrifugally dewatering the material liquid with ferrous sulfate crystal to obtain ferrous sulfate heptahydrate product as reductant and water purifying agent; and returning material liquid generated in dewatering for reuse. The present invention can avoid environmental pollution and lower production cost.
Description
Technical Field
The invention relates to a method for treating and utilizing industrial wastewater, in particular to a method for treating and recycling titanium dioxide waste liquid by a hydrochloric acid method.
Background
Titanium dioxide has been industrialized since 1908, and is widely used in the industrial fields of coatings, plastics, paints, chemical fibers, rubbers, medicines, cosmetics and the like, and is considered to be one of the best inorganic pigments in the world. Titanium dioxide is usually produced by a sulfuric acid method, and although the method is relatively economical, waste liquid generated in the production process seriously pollutes the environment. The treatment and utilization of waste liquid generated in titanium dioxide production by sulfuric acid process has been reported, for example, 1994, volume 24, volume 3, reports the process conditions and process flows of producing industrial manganese sulfate from waste sulfuric acid obtained after titanium dioxide production by sulfuric acid process, waste water and waste residue treatment, product quality and cost accounting, environmental benefits and economic evaluation. In recent years, the number of enterprises adopting the hydrochloric acid method to produce titanium dioxide is gradually increased, and about 5000 tons of titanium dioxide is produced by the hydrochloric acid method in China in 2001 according to related reports; it was estimated that about 14 tons of waste liquid would be produced per one ton of titanium dioxide produced, and about 70000 tons of waste liquid would be produced per 5000 tons of titanium dioxide produced. The waste liquid contains more ferrous chloride and free acid, and if the waste liquid is directly discharged without being treated, the environment is seriously polluted, and the waste of resources is caused. At present, most enterprises adopting hydrochloric acid method to produce titanium dioxide have no policy on pollution caused by the generated waste liquid, and some enterprises buy a large number of farmlands as a waste liquid discharge site for avoiding paying the pollution discharge cost; some enterprises do partial treatment on the waste liquid, but the pollution problem is not solved fundamentally.
Disclosure of Invention
The invention aims to provide a method for treating and recycling titanium dioxide waste liquid by a hydrochloric acid method, which can not only fundamentally solve the problem of environmental pollution caused by the titanium dioxide waste liquid, but also recycle useful components in the waste liquid and reduce the production cost of titanium dioxide.
The invention is provided on the basis of analyzing the components of titanium dioxide waste liquid by hydrochloric acid method. The waste liquid was analyzed to contain about 19.6% ferrous chloride and about 12.3% free acid. Sulfuric acid is added to the waste liquid, and the following chemical reactions occur after heating:
the ferrous sulfate heptahydrate and the hydrogen chloride gas generated by the reaction can be recycled, and the rest waste liquid is not discharged outwards and can be returned to be mixed with newly generated titanium dioxide waste liquid for secondary treatment.
The invention relates to a method for treating and recycling titanium dioxide waste liquid by a hydrochloric acid method, which comprises the following steps:
(1) preparing materials: taking the titanium dioxide waste liquid and the concentrated sulfuric acid according to the weight ratio of 1: 0.10-0.25, injecting the titanium dioxide waste liquid and the concentrated sulfuric acid into an enamel reaction kettle with a cover, and starting an acid-resistant pump arranged at the bottom of the enamel reaction kettle to uniformly mix the titanium dioxide waste liquid and the concentrated sulfuric acid;
(2) fractional distillation: feeding the material liquid mixed uniformly in the burdening process into an external heating type graphite evaporator to be heated by steam, controlling the initial temperature to be 60-70 ℃, then gradually raising the temperature to 120-130 ℃ to stop heating so as to generate chemical reaction, and discharging the generated hydrogen chloride gas from an exhaust port of the external heating type graphite evaporator to enter a graphite falling film absorber; keeping part of the generated ferrous sulfate crystals and the ferrous sulfate supersaturated solution in an external heating type graphite evaporator for continuous heating, stopping steam heating when the temperature is raised to 120-130 ℃, and immediately putting the ferrous sulfate supersaturated solution and part of the ferrous sulfate crystals into a crystallization tank;
(3) absorption: when the hydrogen chloride gas generated in the fractionation process enters a graphite falling film absorber, the hydrogen chloride gas is absorbed by dilute hydrochloric acid to form concentrated hydrochloric acid; the temperature of the feed liquid in the external heating type graphite evaporator is gradually increased, and the generated hydrogen chloride gas is gradually reduced; when the temperature is close to 110 ℃, the feed liquid is boiled, hydrogen chloride gas and water vapor are discharged from an external heating type graphite evaporator, and the obtained dilute hydrochloric acid is put into a storage tank;
(4) cooling and crystallizing: feeding the supersaturated ferrous sulfate solution and part of ferrous sulfate crystals discharged from the external heating graphite evaporator into a crystallization tank, naturally cooling to room temperature, and crystallizing the supersaturated ferrous sulfate solution;
(5) and (3) centrifugal dehydration: transferring the feed liquid containing ferrous sulfate crystals in the cooling crystallization process into a centrifugal machine for dehydration treatment to obtain ferrous sulfate heptahydrate commodity; and returning the feed liquid left after dehydration to be mixed with newly generated titanium dioxide waste liquid for reutilization.
The concentration of concentrated sulfuric acid used in the batching procedure is 80-98%.
The concentration of the hydrochloric acid obtained from the absorption process is between 12 and 32 percent, and when the concentration is lower, hydrogen chloride gas can be introduced to improve the concentration.
The ferrous sulfate heptahydrate obtained from the centrifugal dehydration process is dried to obtain a commercial ferrous sulfate monohydrate. Can be used as feed additive.
The invention has the following advantages: the process flow is short, no special equipment is needed, and the investment is low; the recovery and treatment rate of the waste liquid is high and can reach more than 98 percent, thereby fundamentally solving the problem of environmental pollution caused by titanium dioxide waste liquid produced by a hydrochloric acid method; the concentrated hydrochloric acid obtained by treatment and recovery can be directly returned to be used for producing titanium dioxide, and the ferrous sulfate heptahydrate directly obtained by treatment can be used as a reducing agent or a water purifying agent and used for manufacturing ink, protecting wood and the like to obtain ferrous sulfate monohydrate commodities. Can be used as feed additive. Thereby greatly reducing the production cost of the titanium dioxide from 4700 yuan per ton to 2200 yuan per ton.
Drawings
FIG. 1 is a schematic process flow diagram of the present invention.
Detailed Description
The first embodiment is as follows: referring to fig. 1, the titanium dioxide waste liquid and concentrated sulfuric acid are weighed according to the weight ratio of 1: 0.17. 1300Kg of titanium dioxide waste liquid and 221Kg of sulfuric acid with the concentration of 93 percent are taken and injected into an enamel reaction kettle with a cover, and an acid-proof pump arranged at the bottom of the enamel reaction kettle is started to uniformly mix the titanium dioxide waste liquid and the sulfuric acid;
the material liquid mixed evenly in the batching procedure is input into an external heating type graphite evaporator and is heated and fractionated by steam. Controlling the initial temperature to be 65 +/-5 ℃, then gradually raising the temperature to 125 +/-5 ℃ to stop heating, enabling the temperature to generate chemical reaction, and discharging the generated hydrogen chloride gas from an exhaust port of an external heating type graphite evaporator to enter a graphite falling film absorber; keeping part of the generated ferrous sulfate crystals and the ferrous sulfate supersaturated solution in an external heating type graphite evaporator for continuous heating, stopping steam heating when the temperature is raised to 125 ℃, and immediately putting the ferrous sulfate supersaturated solution and part of the ferrous sulfate crystals into a crystallization tank;
when the hydrogen chloride gas generated in the fractionation process enters a graphite falling film absorber, the hydrogen chloride gas is absorbed by dilute hydrochloric acid to obtain concentrated hydrochloric acid; the generated hydrogen chloride gas is gradually reduced along with the gradual rise of the temperature of the feed liquid in the external heating type graphite evaporator; when the temperature is close to 110 ℃, the feed liquid is boiled, hydrogen chloride gas and water vapor are discharged from an external heating type graphite evaporator, and the obtained dilute hydrochloric acid is put into a storage tank;
the supersaturated solution of ferrous sulfate and part of ferrous sulfate crystal discharged from the external heating graphite evaporator enter a crystallization tank, and the crystallization is naturally cooled to room temperature, so that the supersaturated solution of ferrous sulfate is crystallized;
transferring the feed liquid containing ferrous sulfate crystals in the cooling crystallization process into a centrifugal machine for dehydration treatment to obtain ferrous sulfate heptahydrate commodity; and returning the feed liquid left after dehydration to be mixed with newly generated titanium dioxide waste liquid for reutilization.
The ferrous sulfate heptahydrate obtained from the centrifugal dehydration process is dried to obtain a commercial ferrous sulfate monohydrate. Can be used as feed additive.
When the concentration of hydrochloric acid obtained from the absorption process is low, hydrogen chloride gas can be introduced to increase the concentration of hydrochloric acid so as to return to the titanium dioxide production.
Example two: referring to fig. 1, the titanium dioxide waste liquid and concentrated sulfuric acid are weighed according to the weight ratio of 1: 0.10. Injecting 1000Kg of titanium dioxide waste liquid and 100Kg of sulfuric acid with the concentration of 90% into an enamel reaction kettle with a cover, and starting an acid-resistant pump arranged at the bottom of the enamel reaction kettle to uniformly mix the titanium dioxide waste liquid and the sulfuric acid; the subsequent procedure was the same as in example one.
Example three: referring to fig. 1, the titanium dioxide waste liquid and concentrated sulfuric acid are weighed according to the weight ratio of 1: 0.25. Injecting 1200Kg of titanium dioxide waste liquid and 300Kg of sulfuric acid with the concentration of 95% into an enamel reaction kettle with a cover, and starting an acid-resistant pump arranged at the bottom of the enamel reaction kettle to uniformly mix the titanium dioxide waste liquid and the sulfuric acid; the subsequent procedure was the same as in example one.
Claims (4)
1. The hydrochloric acid process titanium dioxide waste liquid treating and regenerating process includes the following steps:
(1) preparing materials: the titanium dioxide waste liquid and the concentrated sulfuric acid are taken according to the weight ratio of 1: 0.10-0.25, and are injected into an enamel reaction kettle with a cover to be uniformly mixed;
(2) fractional distillation: feeding the material liquid mixed uniformly in the burdening process into an external heating type graphite evaporator to be heated by steam, controlling the initial temperature to be 60-70 ℃, then gradually raising the temperature to 120-130 ℃ to stop heating so as to generate chemical reaction, and dischargingthe generated hydrogen chloride gas from an exhaust port of the external heating type graphite evaporator to enter a graphite falling film absorber; keeping part of the generated ferrous sulfate crystals and the ferrous sulfate supersaturated solution in an external heating type graphite evaporator for continuous heating, stopping steam heating when the temperature is raised to 120-130 ℃, and immediately putting the ferrous sulfate supersaturated solution and part of the ferrous sulfate crystals into a crystallization tank;
(3) absorption: when the hydrogen chloride gas generated in the fractionation process enters a graphite falling film absorber, the hydrogen chloride gas is absorbed by dilute hydrochloric acid to form concentrated hydrochloric acid; the temperature of the feed liquid in the external heating type graphite evaporator is gradually increased, and the generated hydrogen chloride gas is gradually reduced; when the temperature is close to 110 ℃, the feed liquid is boiled, hydrogen chloride gas and water vapor are discharged from an external heating type graphite evaporator, and the obtained dilute hydrochloric acid is put into a storage tank;
(4) cooling and crystallizing: feeding the supersaturated ferrous sulfate solution and part of ferrous sulfate crystals discharged from the external heating graphite evaporator into a crystallization tank, naturally cooling to room temperature, and crystallizing the supersaturated ferrous sulfate solution;
(5) and (3) centrifugal dehydration: transferring the feed liquid containing ferrous sulfate crystals in the cooling crystallization process into a centrifugal machine for dehydration treatment to obtain ferrous sulfate heptahydrate commodity; and returning the feed liquid left after dehydration to be mixed with newly generated titanium dioxide waste liquid for reutilization.
2.The method for treating and recycling titanium dioxide waste liquor produced by hydrochloric acid process according to claim 1, wherein the concentration of concentrated sulfuric acid used in the blending process is 80-98%.
3. The method for treating and recycling titanium dioxide waste liquid by hydrochloric acid process according to claim 1, wherein the concentration of hydrochloric acid obtained from the absorption step is between 12% and 32%, and when the concentration is lower, hydrogen chloride gas can be introduced to increase the concentration.
4. The method for treating and recycling titanium dioxide waste liquid obtained by hydrochloric acid process according to claim 1, wherein the ferrous sulfate heptahydrate obtained from the centrifugal dehydration step is dried to obtain a commercial ferrous sulfate monohydrate.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102276086A (en) * | 2011-07-21 | 2011-12-14 | 同济大学 | Centrifugation-microflocculation combined method for regeneration treatment of titanium dioxide production wastewater |
| CN103708566A (en) * | 2013-12-26 | 2014-04-09 | 攀枝花东方钛业有限公司 | Method for improving filtering performance of ferrous sulfate |
| CN104016415A (en) * | 2014-05-29 | 2014-09-03 | 龚家竹 | Comprehensive utilization production method using hydrochloric acid method artificial rutile production waste liquid |
| CN106630398A (en) * | 2016-12-02 | 2017-05-10 | 国家海洋局天津海水淡化与综合利用研究所 | Method for treating high-salt organic wastewater |
| CN115140711A (en) * | 2022-07-06 | 2022-10-04 | 北京水木方科技有限公司 | Method for regenerating hydrochloric acid by using sulfuric acid for iron-containing waste hydrochloric acid |
-
2004
- 2004-06-10 CN CN 200410022777 patent/CN1706752A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102276086A (en) * | 2011-07-21 | 2011-12-14 | 同济大学 | Centrifugation-microflocculation combined method for regeneration treatment of titanium dioxide production wastewater |
| CN103708566A (en) * | 2013-12-26 | 2014-04-09 | 攀枝花东方钛业有限公司 | Method for improving filtering performance of ferrous sulfate |
| CN103708566B (en) * | 2013-12-26 | 2015-07-22 | 攀枝花东方钛业有限公司 | Method for improving filtering performance of ferrous sulfate |
| CN104016415A (en) * | 2014-05-29 | 2014-09-03 | 龚家竹 | Comprehensive utilization production method using hydrochloric acid method artificial rutile production waste liquid |
| CN104016415B (en) * | 2014-05-29 | 2016-04-13 | 龚家竹 | By the comprehensive utilization production method of hydrochloric acid method Production of Artificial Rutile waste liquid |
| CN106630398A (en) * | 2016-12-02 | 2017-05-10 | 国家海洋局天津海水淡化与综合利用研究所 | Method for treating high-salt organic wastewater |
| CN106630398B (en) * | 2016-12-02 | 2019-07-16 | 自然资源部天津海水淡化与综合利用研究所 | A method of handling high salt organic waste water |
| CN115140711A (en) * | 2022-07-06 | 2022-10-04 | 北京水木方科技有限公司 | Method for regenerating hydrochloric acid by using sulfuric acid for iron-containing waste hydrochloric acid |
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