CN112624189B - Method and system for recycling waste acid and white water of titanium dioxide produced by sulfuric acid process - Google Patents
Method and system for recycling waste acid and white water of titanium dioxide produced by sulfuric acid process Download PDFInfo
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- CN112624189B CN112624189B CN202110047642.7A CN202110047642A CN112624189B CN 112624189 B CN112624189 B CN 112624189B CN 202110047642 A CN202110047642 A CN 202110047642A CN 112624189 B CN112624189 B CN 112624189B
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- C01G23/00—Compounds of titanium
- C01G23/04—Oxides; Hydroxides
- C01G23/047—Titanium dioxide
- C01G23/053—Producing by wet processes, e.g. hydrolysing titanium salts
- C01G23/0532—Producing by wet processes, e.g. hydrolysing titanium salts by hydrolysing sulfate-containing salts
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Abstract
The invention belongs to the field of titanium dioxide production, and discloses a recycling method and a recycling system for waste acid and white water of sulfuric acid method titanium dioxide, wherein the system comprises a waste acid treatment system, an acid water treatment system, a prewashing white water treatment system and a white washing water treatment system, and the waste acid treatment system is used for treating the waste acid to obtain ferrous sulfate monohydrate, an acidolysis acid serving as the acidolysis system and condensed water serving as the washing water of a plate washing frame; the acid water treatment system is used for treating acid water to obtain a clear liquid serving as make-up water of the acidolysis leaching system and a concentrated liquid serving as a raw material of the iron gathering system; the prewashing white water treatment system is used for treating prewashing white water to obtain clear liquid serving as make-up water of the acidolysis leaching system and concentrated liquid serving as a raw material of the polyferric system; the first washing white water treatment system is used for treating the first washing white water to obtain a clear liquid serving as the washing water of the second washing plate frame and a concentrated liquid serving as the pre-washing water of the first washing plate frame. The recovery system can reduce the powder loss rate in the washing process and the water consumption in the washing stage, and does not discharge acidic wastewater.
Description
Technical Field
The invention belongs to the technical field of titanium dioxide production, and particularly relates to a method and a system for recycling waste acid and white water of sulfuric acid process titanium dioxide.
Background
The titanium dioxide is mainly produced by a sulfuric acid method at the present stage in China. The production process of the titanium dioxide by the sulfuric acid method has mature technology, simple equipment and low requirements on raw materials, but has large discharge of three wastes and high treatment cost. Especially waste acid generated by metatitanic acid preparation (1 ton titanium dioxide product is produced, and 4-7 t waste acid is generated) and purification treatment after metatitanic acid preparation is finished; and the traditional washing procedure adopts a plate-and-frame washing process, a large amount of washing white water (1 ton of titanium dioxide product is produced, and 20-30 t of white water is produced) is produced, and the white water mainly contains metatitanic acid, sulfuric acid and ferrous sulfate.
At present, the conventional treatment mode of white water is that the white water is subjected to neutralization treatment and then is merged with waste water of other sections of a whole plant and then is uniformly treated, so that a large amount of powder products are lost, sulfuric acid and iron in the white water cannot be effectively utilized, and a large amount of red yellow gypsum is generated. In order to respond to the requirement of environmental management and improve the enterprise competitiveness, an economic and effective technical scheme is urgently needed to be found in the titanium dioxide industry aiming at the treatment of waste acid and white water.
Disclosure of Invention
The invention aims to provide a method and a system for recycling waste acid and white water of titanium dioxide by a sulfuric acid method, which can reduce the powder loss rate in the washing process and water consumption in the washing stage, and have no acidic wastewater discharge in the whole process.
The technical scheme provided by the invention is as follows:
in one aspect, a recycling system for waste acid and white water of titanium dioxide produced by a sulfuric acid method is provided, and is used for recycling waste acid and white water produced by a plate and frame system, and the recycling system comprises:
the waste acid treatment system is used for treating waste acid generated by filtering the plate washing frame to obtain ferrous sulfate monohydrate, acidolysis acid used as the acidolysis system and condensed water used as water washing water of the plate washing frame;
the acid water treatment system is used for filtering and separating acid water generated by prewashing the plate washing frame to obtain a first clear liquid used as make-up water of the acidolysis leaching system and a first concentrated solution used as a raw material of the iron gathering system;
the prewashing white water treatment system is used for filtering and separating prewashing white water generated by prewashing a plate washing frame to obtain a second clear liquid used as make-up water of the acidolysis leaching system and a second concentrated liquid used as a raw material of the iron gathering system;
and the white washing water treatment system is used for filtering and separating the white washing water generated by washing the first washing plate frame to obtain a third clear liquid used as the washing water of the second washing plate frame and a third concentrated liquid used as the pre-washing water of the first washing plate frame.
Further, the waste acid treatment system comprises a pretreatment unit, a calcination tail gas unit, a membrane treatment unit and an evaporation unit which are connected in sequence;
the pretreatment unit is used for removing powder in waste acid generated by filtering the plate washing frame to obtain fourth clear liquid;
the calcination tail gas unit is used for carrying out spray concentration on the fourth clear liquid;
the membrane processing unit is used for filtering the concentrated fourth clear liquid and removing powder and a small amount of crystallized ferrous sulfate in the concentrated fourth clear liquid;
the evaporation unit is used for carrying out evaporation treatment on the fourth clear liquid after filtration treatment to obtain ferrous sulfate monohydrate, 70 acid used as acidolysis acid of the acidolysis system and condensed water used as washing water of a washing plate frame.
Further, still include:
and the waste acid film treatment system is used for removing powder from part of waste acid generated by the plate washing frame to obtain clear liquid used as a raw material of the polyferric system.
Further, the acid water treatment system comprises an acid water membrane filtration unit and an acid water membrane separation unit which are sequentially connected, wherein the acid water membrane filtration unit is used for removing powder in the acid water, and the acid water membrane separation unit is used for performing ion separation on acid water clear liquid after the powder is removed to obtain the first clear liquid and the first concentrated solution;
the prewashing white water treatment system comprises a prewashing white water membrane filtering unit and a prewashing white water membrane separation unit which are sequentially connected, wherein the prewashing white water membrane filtering unit is used for removing powder in prewashing white water, and the prewashing white water membrane separation unit is used for carrying out ion separation on the prewashing white water clear liquid after the powder is removed to obtain a second clear liquid and a second concentrated liquid;
the white washing water treatment system comprises a white washing water film filtering unit and a white washing water film separating unit which are sequentially connected, wherein the white washing water film filtering unit is used for removing powder in white washing water, and the white washing water film separating unit is used for carrying out ion separation on white washing water clear liquid after the powder is removed to obtain third clear liquid and third concentrated liquid.
On the other hand, the recycling method of the waste acid of the sulfuric acid method titanium dioxide and the white water is also provided, and comprises the following steps:
treating waste acid generated by filtering a plate washing frame to obtain ferrous sulfate monohydrate, 70 acid and condensed water, sending the 70 acid into an acidolysis system to serve as acidolysis acid of the acidolysis system, and returning the condensed water to the plate washing frame to serve as plate washing frame washing water;
filtering and separating acid water generated by prewashing a plate washing frame to obtain a first clear liquid and a first concentrated solution, sending the first clear liquid into an acidolysis leaching system as supplementing water of the acidolysis leaching system, and sending the first concentrated solution into an iron gathering system to prepare iron gathering;
filtering and separating prewashing white water generated by prewashing a plate washing frame to obtain a second clear liquid and a second concentrated liquid, sending the second clear liquid into an acidolysis leaching system to serve as supplementary water of the acidolysis leaching system, and sending the second concentrated liquid into a polyferric system to prepare polyferric;
and filtering and separating first washing white water generated by washing the first washing plate frame to obtain third clear liquid and third concentrated liquid, sending the third clear liquid into the second washing plate frame to serve as washing water of the second washing plate frame, and sending the third concentrated liquid into the first washing plate frame to serve as pre-washing water of the first washing plate frame.
Further, the step of processing waste acid generated by filtering a plate washing frame to obtain ferrous sulfate monohydrate, 70 acid and condensed water specifically comprises the following steps:
pretreating waste acid generated by filtering a plate washing frame, removing powder in the waste acid to obtain fourth clear liquid, and returning the powder to the plate washing frame for water washing;
spraying and concentrating the fourth clear liquid by using calcination tail gas;
filtering the fourth clear liquid after spray concentration, and removing powder and a small amount of crystalline ferrous sulfate in the fourth clear liquid after concentration;
evaporating the fourth clear liquid after filtering treatment to obtain 70 acid, ferrous sulfate monohydrate and condensed water, sending the 70 acid into an acidolysis leaching system to be used as acidolysis acid of an acidolysis section, and sending the condensed water into a plate washing frame to be used as washing water make-up water.
Further, still include:
performing solid-liquid separation on a part of waste acid generated by filtering the plate washing frame, removing powder in the waste acid, and returning the powder to the plate washing frame for water washing;
and feeding the fifth clear liquid into a polyferric system to prepare the polyferric.
Further, the filtering and separating treatment of acid water generated by prewashing of a plate washing frame to obtain a first clear liquid and a first concentrated liquid specifically comprises:
carrying out solid-liquid separation on acid water generated by prewashing a plate washing frame, and removing powder in the acid water to obtain acid water clear liquid;
carrying out ion separation on acid water clear liquid generated by solid-liquid separation to obtain the first clear liquid and the first concentrated solution;
the filtering and separating treatment of the prewashing white water generated by prewashing the plate frame to obtain the second clear liquid and the second concentrated liquid specifically comprises the following steps:
carrying out solid-liquid separation on pre-washing white water generated by pre-washing a plate washing frame, and removing powder in the pre-washing white water to obtain pre-washing white water clear liquid;
performing ion separation on the prewashed white water clear liquid generated by solid-liquid separation to obtain the second clear liquid and the second concentrated solution;
the filtration and separation treatment of the white washing water generated by washing the plate frame to obtain the third clear liquid and the third concentrated liquid specifically comprises the following steps:
carrying out solid-liquid separation on a white washing water generated by washing a plate washing frame, and removing powder in the white washing water to obtain a white washing water clear liquid;
and carrying out ion separation on a white washing water clear solution generated by solid-liquid separation to obtain the third clear solution and the third concentrated solution.
Further, still include:
and returning powder generated by solid-liquid separation of the waste acid, powder generated by solid-liquid separation of the acid water, powder generated by solid-liquid separation of the prewashing white water and powder generated by solid-liquid separation of the prewashing white water to a plate washing frame for water washing.
Further, the content of iron ions in the first clear liquid is less than 5000ppm, and the content of iron ions in the first concentrated solution is more than 50000pm;
the content of iron ions in the second clear liquid is less than 500ppm, and the content of iron ions in the second concentrated liquid is more than 50000pm;
the iron ion content in the third clear liquid is less than 2ppm.
The method and the system for recycling the waste acid and the white water of the titanium dioxide by the sulfuric acid method can bring the following beneficial effects:
(1) In order to improve the recovery rate of titanium dioxide, reduce water consumption of washing and improve the recycling rate of water washing, the invention combines the water quality characteristics of waste acid and white water to develop a novel method and a novel system for recycling the waste acid and the white water of the titanium dioxide by a sulfuric acid method, the waste acid, acid water, pre-washing water and washing white water generated by a plate washing frame are respectively treated by a waste acid treatment system, an acid water treatment system, a pre-washing white water treatment system and a washing white water treatment system, powder in the waste acid and the white water can be intercepted, zero loss of powder products in the washing process is realized, and the generated clear liquid and concentrated liquid can be reused in an acidolysis working section, a washing working procedure and the like, no acidic waste water is discharged, no neutralization treatment is needed, and the water consumption in the washing stage is reduced to 7-10 t/tTiO 2 (7-10 t water/tTiO consumed) 2 Wherein 2-3 t of the water is additional desalted water, and the rest part is acidolysis leaching water of the ortho-acid lysis leaching system);
(2) Powder recovered by all membrane filtration units and membrane treatment units in the system is recycled to a plate washing frame for water washing, so that zero emission of the powder can be realized;
(3) According to the waste acid treatment system, the tail gas calcining unit completely utilizes waste heat in a titanium powder plant to concentrate waste acid, so that the waste heat is effectively utilized;
(4) According to the waste acid treatment system, the membrane treatment unit further removes powder and titanyl sulfate in the waste acid after the calcination tail gas is concentrated, so that the cleaning period of the evaporation unit is shortened;
(5) The waste acid film treatment system is added, so that the waste acid can be divided into two parts for treatment, and the waste acid recycling efficiency is improved;
(6) The 70 acid recycled to the acidolysis system after the waste acid treatment reduces the 98 acid consumption of the acidolysis system, wherein the 98 acid consumption is reduced from the original 3-4 t/tTiO 2 Reduced to 1-2 t/tTiO 2 ；
(7) The water generated by the prewashing in the invention is divided into two parts of acid water and prewashing white water, and the main purposes are as follows: (1) the content of titanyl sulfate pollutants in the acid water and the pre-washing white water is different, the waste water of the acid water and the pre-washing white water is distinguished so as to conveniently determine the chemical washing period of a filtering device and a separating device, and the design of one-open one-standby equipment can be implemented for the waste water with more titanyl sulfate pollutants in the acid water, so that the service cycle of the chemical washing device is prolonged; (2) the acid water is obtained by pre-washing after waste acid is separated by a washing plate frame, the acid content and the iron content of the acid water are higher than those of pre-washing white water, the solubility and the acid content of iron ions form an inverse relation, the higher the acid content is, the lower the solubility of the iron ions is, and the higher the recovery rate can be obtained by the separation treatment compared with the mixing treatment for a membrane separation unit;
(8) The acid water, the prewashing white water and the first-washing white water are subjected to water splitting treatment in order to maintain the acid balance in the system, and because the requirement on the acidity of a titanium dioxide washing qualified material is not higher than 3 percent (the acidity of the qualified material is higher than 3 percent, the quality of the titanium dioxide is reduced, and the calcining difficulty is improved), the acid brought out by the early prewashing of the acid water and the prewashing white water cannot be reused as the washing water make-up water, and directly enters an acidolysis leaching system and a polyferric system after membrane separation treatment, and the first-washing white water generated by plate frame washing after the system is subjected to prewashing acidity reduction can be treated and then continuously reused as the washing water make-up water;
(9) In the invention, clear liquid generated after the acid water and the prewashing white water are treated enters an acidolysis leaching system, so that the acidolysis leaching system does not need to add acid to inhibit hydrolysis of acidolysis materials (the materials are subjected to acidolysis first and then to acidolysis leaching, and the original acid leaching water refers to reverse osmosis concentrated water in a plant).
Drawings
The above characteristics, technical features, advantages and implementation of the method and system for recycling waste acid and white water of titanium dioxide produced by sulfuric acid process will be further described in the following preferred embodiments in a clear and understandable manner with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a system for recycling waste acid and white water from titanium dioxide produced by a sulfuric acid process;
FIG. 2 is a schematic flow chart of a method for recycling waste acid and white water of titanium dioxide produced by a sulfuric acid process.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, without inventive effort, other drawings and embodiments can be derived from them.
For the sake of simplicity, the drawings only schematically show the parts relevant to the present invention, and they do not represent the actual structure as a product. In addition, in order to make the drawings concise and understandable, components having the same structure or function in some of the drawings are only schematically illustrated or only labeled. In this document, "one" means not only "only one" but also a case of "more than one".
It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
In this context, it is to be understood that, unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, in the description of the present application, the terms "first", "second", and the like are used only for distinguishing the description, and are not intended to indicate or imply relative importance.
The invention provides a specific embodiment of a recycling system of waste acid and white water of titanium dioxide by a sulfuric acid method, which comprises a waste acid treatment system, an acid water treatment system, a prewashing white water treatment system and a white water washing treatment system, wherein the waste acid treatment system comprises a pretreatment unit, a calcination tail gas unit, a membrane treatment unit and an evaporation unit which are sequentially connected, and is used for treating waste acid generated by filtering a plate washing frame to obtain ferrous sulfate monohydrate, acidolysis acid used as an acidolysis system and condensed water used as water for washing the plate washing frame.
The acid water treatment system comprises an acid water membrane filtering unit and an acid water membrane separation unit which are sequentially connected and used for filtering and separating acid water generated by prewashing a plate washing frame to obtain a first clear liquid used as make-up water of the acidolysis leaching system and a first concentrated liquid used as a raw material of the iron gathering system.
The prewashing white water treatment system comprises a prewashing white water membrane filtration unit and a prewashing white water membrane separation unit which are sequentially connected, and is used for filtering and separating prewashing white water generated by prewashing a plate washing frame to obtain a second clear liquid used as make-up water of the acidolysis leaching system and a second concentrated liquid used as a raw material of the iron gathering system.
And the white washing water treatment system comprises a white washing water film filtering unit and a white washing water film separating unit which are sequentially connected and is used for filtering and separating the white washing water generated by washing the plate frame to obtain a third clear liquid used as the washing water of the two washing plate frames and a third concentrated liquid used as the pre-washing water of the one washing plate frame.
Specifically, the production process of titanium dioxide by a sulfuric acid method mainly comprises the working procedures of acidolysis, hydrolysis, water washing, post-treatment and the like, and the recycling system mainly recycles waste acid and white water generated when a plate-and-frame system filters and washes a hydrolysis material prepared from metatitanic acid. The water washing principle is that the metatitanic acid is intercepted by filtering by utilizing the characteristic that the metatitanic acid is insoluble in water, and then the metatitanic acid is washed by water.
A large amount of waste acid and white water can be generated in the washing process, the waste acid and the white water mainly contain free sulfuric acid, metatitanic acid powder, ferrous sulfate and the like, and the powder is seriously lost, and the serious environmental pollution problem is caused.
The hydrolyzed material generates waste acid after being filtered by a plate washing frame, generates acid water and prewashing white water after being prewashed by the plate washing frame, and generates washing white water after being prewashed by the plate washing frame. The waste acid treatment system is mainly used for treating waste acid generated by filtering a plate washing frame to obtain ferrous sulfate monohydrate and acid with certain acidity, and the acid can be recycled as acidolysis acid of an acidolysis system, wherein the acidolysis system is an acidolysis working section in a titanium dioxide production process by a sulfuric acid method.
A pretreatment unit in the waste acid treatment system is used for removing powder in waste acid generated by filtering a plate washing frame to obtain fourth clear liquid; the calcining tail gas unit is used for spraying and concentrating the fourth clear liquid; the membrane processing unit is used for filtering the concentrated fourth clear liquid and removing powder and a small amount of crystallized ferrous sulfate in the concentrated fourth clear liquid; the evaporation unit is used for carrying out evaporation treatment on the fourth clear liquid after filtration treatment to obtain ferrous sulfate monohydrate, 70 acid used as acidolysis acid of the acidolysis system and condensed water used as washing water of a washing plate frame.
The hydrolysis material is obtained after the preparation of metatitanic acid is finished, waste acid is generated after the hydrolysis material is filtered by a plate washing frame, the waste acid enters a pretreatment unit to remove powder, clear liquid enters a calcination tail gas unit, the calcination tail gas is sprayed and directly subjected to heat exchange concentration until the acidity of sulfuric acid is 30%, solid pollutants in the waste acid are removed in a membrane treatment unit, then the waste acid enters an evaporation unit, the waste acid is concentrated in the evaporation unit until 70 acid with the acidity of 70% is obtained, the 70 acid generated in the evaporation unit can be used as acidolysis acid in the acidolysis section, when the acid is used as the acidolysis acid in the acidolysis section, the 70 acid generated in the evaporation unit needs to be mixed with 98 acid added from the outside to form 87 acid, and then the 87 acid enters the acidolysis section to be used as the acidolysis acid in the acidolysis section. Ferrous sulfate monohydrate produced by the evaporation unit can be directly sold or used as an iron source for producing poly-iron; the condensed water generated by the evaporation unit can be returned to a washing plate frame to be used as the make-up water of the pre-washing water and the washing water.
Because a large amount of waste acid is generated by filtering one plate washing frame, if the waste acid is completely treated by a waste acid treatment system to obtain 70 acid, the output of the 70 acid is far greater than that of acid hydrolysis acid required by an acid hydrolysis working section, therefore, the recovery system also comprises a waste acid membrane treatment system, one part of the waste acid generated by filtering one plate washing frame is sent to the waste acid treatment system for treatment, the other part of the waste acid is sent to the waste acid membrane treatment system for filtration treatment, and clear liquid after powder removal enters a polyferric system for polyferric treatment.
The acid water treatment system is mainly used for filtering and separating acid water generated by a plate washing frame, an acid water membrane filtering unit in the acid water treatment system is used for removing powder in acid water, the acid water membrane separating unit is used for carrying out ion separation on acid water clear liquid after the powder is removed, and intercepting ferrous sulfate in the acid water clear liquid to obtain a first clear liquid and a first concentrated solution, wherein the first clear liquid can be used as make-up water of an acidolysis leaching system and recycled to an acidolysis workshop section to replace reverse osmosis concentrated water of the acidolysis leaching system; the first concentrated solution can be used as poly-iron by a de-poly-iron system.
The prewashing white water treatment system is mainly used for filtering and separating prewashing white water generated by a washing plate frame, a prewashing white water membrane filtration unit in the prewashing white water treatment system is used for removing powder in the prewashing white water, and a prewashing white water membrane separation unit is used for carrying out ion separation on the prewashing white water clear liquid after the powder is removed to obtain a second clear liquid and a second concentrated solution, wherein the second clear liquid can be used as make-up water of an acidolysis leaching system and recycled to an acidolysis working section to replace reverse osmosis concentrated water of the acidolysis leaching system; the second concentrated solution can be used as iron polymer by an iron polymer removing system.
A wash white water processing system mainly used filters and separates the processing to a wash white water that a wash plate frame produced, a wash white water film filter unit in a wash white water processing system is used for getting rid of the powder in a wash white aquatic, a wash white water film separation unit is used for carrying out ion separation to the wash white water clear liquid after getting rid of the powder, obtains third clear liquid and third concentrate, and the third clear liquid can be collected and drawn into two wash water buffer tanks, supplies a small amount of desalinized water back and uses as two wash water circulations, and the third concentrate can be as the first prewashing water of material of hydrolysising in a wash plate frame.
When the recycling system is used for producing titanium dioxide by adopting a sulfuric acid method, after a hydrolyzed material is filtered by a plate washing frame to generate waste acid, the plate washing frame is pre-washed by third concentrated solution generated by a white water washing treatment system, acid water generated during pre-washing enters the acid water treatment system for filtration and separation treatment, the plate washing frame pre-washed by the third concentrated solution is pre-washed by soaking water in an original acidolysis working section, pre-washing white water generated at the time enters the white water pre-washing treatment system for filtration and separation treatment, and finally white water generated by washing the plate washing frame by desalted water enters the white water washing treatment system for filtration and separation treatment.
The waste acid, the acid water, the prewashing white water treatment system and the washing white water treatment system which are generated by a washing plate frame are respectively treated by the waste acid treatment system, the acid water treatment system, the prewashing white water treatment system and the washing white water treatment system, powder in the waste acid and the white water can be intercepted, the powder product loss is reduced, the titanium dioxide recovery rate is improved, and the generated clear liquid and concentrated liquid can be reused in an acidolysis working section and a washing working procedure or used as a polyferric raw material, so that the water washing water consumption of the washing working procedure is reduced to 7-10 t/tTiO 2 (production of 1 ton of TiO) 2 The water consumption of the washing is 7-10 tons) to improve the cyclic utilization rate of the washing water, and the whole process has no acid wastewater discharge, does not need neutralization treatment and does not pollute the environment.
In this embodiment, the pretreatment unit, the membrane treatment unit, and the membrane filtration unit are mainly used to intercept solids to realize solid-liquid separation, and the membrane separation unit is mainly used to intercept ferrous sulfate ions.
After the recycling system of the embodiment is adopted, in the production process of titanium dioxide by a sulfuric acid method, the prewashing water of a washing plate frame mainly comes from three parts: condensed water generated by the evaporation unit, third concentrated solution generated by a white washing water treatment system and soaking water generated by an acidolysis section.
The acid hydrolysis acid of the acid hydrolysis section comes from two parts: 70 acid generated by the evaporation unit and 98 acid supplemented outside the system.
Make-up water for the acidolysis leaching system comes from two parts: the first clear liquid produced by the acid water treatment system and the second clear liquid produced by the prewashing white water treatment system.
The raw materials required by the iron gathering system are from three parts: clear liquid generated by the waste acid membrane treatment system, first concentrated liquid generated by the acid water treatment system and second concentrated liquid generated by the prewashing white water treatment system.
The pretreatment unit, the membrane treatment unit and the membrane filtration unit in the embodiment have ultrahigh retention rate on powder, and the powder loss rate of the system is 0%.
The recovery rate of acid water of the acid water membrane separation unit is more than 20 percent (the first clear liquid generated by the acid water membrane separation unit is more than 20 percent than that generated by the acid water membrane filtration unit), the content of iron ions in the generated first clear liquid is less than 5000ppm, and the content of iron ions in the generated first concentrated liquid is more than 50000ppm.
The recovery rate of the prewashing white water membrane separation unit is more than 80 percent (the second clear liquid generated by the prewashing white water membrane separation unit is more than 80 percent than the prewashing white water membrane filtration unit clear liquid), the content of iron ions in the generated second clear liquid is less than 500ppm, and the content of iron ions in the generated second concentrated liquid is more than 50000ppm.
The recovery rate of the first washing white water membrane separation unit is more than 80 percent (the third clear liquid generated by the first washing white water membrane separation unit is more than 80 percent than the clear liquid generated by the first washing white water membrane filtration unit), and the iron ion content in the generated third clear liquid is less than 2ppm.
The plate frame washing system is divided into two parts, namely a plate washing frame system and a plate washing frame system, wherein the plate washing frame system outputs a water washing sleeve for the plate washing frame system; after the water produced by the first plate washing frame system is treated by the membrane filtration and membrane separation unit, the obtained clear water jacket is used for the second plate washing frame system.
The concentration of sulfuric acid in the plate frame washing and white water washing film separation water circulation system is 1-3%.
The consumption of the water obtained by acidolysis leaching of the whole system is less than 7t/tTiO 2 I.e. 1 ton of TiO produced 2 The leaching water consumption consumed by the whole system water washing is less than 7 tons.
The consumption of fresh desalted water of the whole system is less than 2.5t/tTiO 2 。
The discharged material of the whole system is ferrous sulfate monohydrate, the discharge amount of the ferrous sulfate monohydrate is less than 1t/tTiO 2 Wherein the concentration of the ferrous sulfate monohydrate is more than 80 percent.
The invention also provides a specific embodiment of a recycling method of a recycling system of waste acid of titanium dioxide and white water produced by a sulfuric acid method, as shown in fig. 2, the recycling method comprises the following steps:
treating waste acid generated by filtering a plate washing frame to obtain ferrous sulfate monohydrate, 70 acid and condensed water, sending the 70 acid into an acidolysis system to serve as acidolysis acid of the acidolysis system, and sending the condensed water into the plate washing frame to serve as plate washing frame washing water;
filtering and separating acid water generated by prewashing a plate washing frame to obtain a first clear liquid and a first concentrated solution, sending the first clear liquid into an acidolysis leaching system as supplementing water of the acidolysis leaching system, and sending the first concentrated solution into a poly-iron system to prepare poly-iron;
filtering and separating prewashing white water generated by prewashing a plate washing frame to obtain a second clear liquid and a second concentrated solution, sending the second clear liquid into an acidolysis leaching system to serve as supplementary water of the acidolysis leaching system, and sending the second concentrated solution into a polyferric system to prepare polyferric;
and (3) filtering and separating the first washing white water generated by washing the first washing plate frame to obtain a third clear liquid and a third concentrated liquid, sending the third clear liquid into the second washing plate frame to serve as the washing water for the second washing plate frame, and sending the third concentrated liquid into the first washing plate frame to serve as the prewashing water for the first washing plate frame, wherein the prewashing water comprises the part of water generated by prewashing and used for generating acid water and prewashing white water.
In this embodiment, the order of the steps may be interchanged according to actual processing logic, and the writing order of the steps does not limit the order of the steps.
Wherein, the waste acid produced by filtering the plate washing frame is treated to obtain ferrous sulfate monohydrate, 70 acid and condensed water, and the method specifically comprises the following steps:
pretreating waste acid generated by filtering the plate washing frame, removing powder in the waste acid to obtain fourth clear liquid, and sending the intercepted powder into the plate washing frame for continuous water washing;
spraying and concentrating the fourth clear liquid by using the calcining tail gas;
filtering the fourth clear liquid after spray concentration, and removing powder and a small amount of crystallized ferrous sulfate in the fourth clear liquid after concentration;
evaporating the fourth clear liquid after filtering treatment to obtain 70 acid and ferrous sulfate monohydrate, sending the 70 acid into an acidolysis system to be used as acidolysis acid of an acidolysis section, and sending condensed water generated by evaporation treatment into a plate washing frame to be used as make-up water for pre-washing water and washing water.
Wherein, still include:
carrying out solid-liquid separation on a part of waste acid generated by filtering a plate washing frame, removing powder in the waste acid, and returning the powder to the plate washing frame for water washing;
and feeding the fifth clear liquid into a polyferric system to prepare the polyferric.
Wherein, wash the board frame and wash the sour water that produces in advance and filter and separation process, obtain first clear liquid and first dope and specifically include:
carrying out solid-liquid separation on acid water generated by prewashing a plate washing frame, and removing powder in the acid water to obtain acid water clear liquid;
carrying out ion separation on acid water clear liquid generated by solid-liquid separation to obtain a first clear liquid and a first concentrated solution;
filtering and separating the prewashing white water generated by prewashing the plate frame to obtain a second clear liquid and a second concentrated liquid, wherein the second clear liquid and the second concentrated liquid specifically comprise:
carrying out solid-liquid separation on pre-washing white water generated by pre-washing a plate washing frame, and removing powder in the pre-washing white water to obtain pre-washing white water clear liquid;
performing ion separation on the prewashed white water clear liquid generated by solid-liquid separation to obtain a second clear liquid and a second concentrated solution;
filtering and separating white washing water generated by washing a plate frame to obtain a third clear liquid and a third concentrated liquid, wherein the third clear liquid and the third concentrated liquid specifically comprise:
carrying out solid-liquid separation on white washing water generated by washing a plate washing frame to remove powder in the white washing water to obtain white washing water clear liquid;
and carrying out ion separation on the first white washing water clear liquid generated by solid-liquid separation to obtain a third clear liquid and a third concentrated liquid.
The powder generated by solid-liquid separation of acid water, the powder generated by solid-liquid separation of prewashed white water and the powder generated by solid-liquid separation of the first washing white water are returned to the plate washing frame for continuous water washing.
Specifically, the sulfuric acid method titanium dioxide production process adopts an additional crystal seed hydrolysis mode to prepare metatitanic acid.
About 85% of waste acid generated after the hydrolyzed material is filtered by a plate washing frame enters a waste acid treatment system, and after the hydrolyzed material is treated by a pretreatment unit, a calcination tail gas unit, a membrane treatment unit and an evaporation unit, the waste acid treatment system generates about 7% (accounting for the proportion of 85% of the waste acid) of powder slurry, about 34% of 70 acid, about 43% of condensed water and about 16% of ferrous sulfate.
About 15% of waste acid generated after the hydrolyzed material is filtered by a plate washing frame enters a waste acid membrane treatment system, and after the waste acid membrane treatment system is used for treating, about 7% of powder slurry and about 93% of clear liquid are generated.
Acid water generated by prewashing of a plate washing frame enters an acid water treatment system, and is treated by a membrane filtration unit and a membrane separation unit, the membrane filtration unit generates about 3% of powder slurry, and the membrane separation unit generates about 22% of first clear liquid and about 75% of first concentrated solution.
The prewashed white water generated by prewashing the plate washing frame enters a prewashed white water treatment system, after the prewashed white water is treated by the membrane filtration unit and the membrane separation unit, the membrane filtration unit generates about 2% of powder slurry, and the membrane separation unit generates about 81% of second clear liquid and about 17% of second concentrated liquid.
A washing white water generated by washing a plate frame enters a washing white water treatment system, after being treated by a membrane filtration unit and a membrane separation unit, the membrane filtration unit generates about 1% of powder slurry, and the membrane separation unit generates about 88% of third clear liquid and about 11% of third concentrated liquid.
It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A recycling system of waste acid and white water of titanium dioxide produced by a sulfuric acid method is used for recycling waste acid and white water produced by filtering and washing a plate-and-frame system, and is characterized by comprising the following components:
the waste acid treatment system is used for treating waste acid generated by filtering the plate washing frame to obtain ferrous sulfate monohydrate, acidolysis acid used as the acidolysis system and condensed water used as water washing water of the plate washing frame;
the acid water treatment system is used for filtering and separating acid water generated by prewashing the plate washing frame to obtain a first clear liquid used as make-up water of the acidolysis leaching system and a first concentrated solution used as a raw material of the iron gathering system;
the prewashing white water treatment system is used for filtering and separating prewashing white water generated by prewashing a plate washing frame to obtain a second clear liquid used as supplementing water of the acidolysis leaching system and a second concentrated solution used as a raw material of the iron gathering system;
the white washing water treatment system is used for filtering and separating the white washing water generated by washing the first washing plate frame to obtain a third clear liquid used as the washing water of the second washing plate frame and a third concentrated liquid used as the pre-washing water of the first washing plate frame;
the prewashing white water treatment system comprises a prewashing white water membrane filtering unit and a prewashing white water membrane separation unit which are sequentially connected, wherein the prewashing white water membrane filtering unit is used for removing powder in prewashing white water, and the prewashing white water membrane separation unit is used for carrying out ion separation on the prewashing white water clear liquid after the powder is removed to obtain the second clear liquid and the second concentrated liquid.
2. The recycling system of waste acid and white water of titanium dioxide by sulfuric acid process according to claim 1,
the waste acid treatment system comprises a pretreatment unit, a calcination tail gas unit, a membrane treatment unit and an evaporation unit which are connected in sequence;
the pretreatment unit is used for removing powder in waste acid generated by filtering the plate washing frame to obtain fourth clear liquid;
the calcination tail gas unit is used for spraying and concentrating the fourth clear liquid;
the membrane processing unit is used for filtering the concentrated fourth clear liquid and removing powder and a small amount of crystallized ferrous sulfate in the concentrated fourth clear liquid;
the evaporation unit is used for carrying out evaporation treatment on the filtered fourth clear liquid to obtain ferrous sulfate monohydrate, 70 acid used as acidolysis acid of an acidolysis system and condensed water used as washing water of a washing plate frame, wherein the 70 acid is 70% sulfuric acid.
3. The recycling system of waste acid and white water of titanium dioxide produced by a sulfuric acid process according to claim 2, further comprising:
and the waste acid film treatment system is used for removing powder from part of waste acid generated by the plate washing frame to obtain clear liquid used as a raw material of the iron gathering system.
4. The recycling system of waste acid and white water of titanium dioxide by sulfuric acid process according to claim 1,
the acid water treatment system comprises an acid water membrane filtration unit and an acid water membrane separation unit which are sequentially connected, wherein the acid water membrane filtration unit is used for removing powder in acid water, and the acid water membrane separation unit is used for carrying out ion separation on acid water clear liquid after the powder is removed to obtain first clear liquid and first concentrated liquid;
the white washing water treatment system comprises a white washing water film filtering unit and a white washing water film separating unit which are sequentially connected, wherein the white washing water film filtering unit is used for removing powder in white washing water, and the white washing water film separating unit is used for carrying out ion separation on white washing water clear liquid after the powder is removed to obtain third clear liquid and third concentrated liquid.
5. A recycling method of waste acid of titanium dioxide and white water by a sulfuric acid method, which is applied to the recycling system of waste acid of titanium dioxide and white water by a sulfuric acid method according to any one of claims 1 to 4, and is characterized by comprising the following steps:
treating waste acid generated by filtering a plate washing frame to obtain ferrous sulfate monohydrate, 70 acid and condensed water, sending the 70 acid into an acidolysis system to serve as acidolysis acid of the acidolysis system, and sending the condensed water into the plate washing frame to serve as plate washing frame washing water, wherein the 70 acid is 70% sulfuric acid;
filtering and separating acid water generated by prewashing a plate washing frame to obtain a first clear liquid and a first concentrated solution, sending the first clear liquid into an acidolysis leaching system as supplementing water of the acidolysis leaching system, and sending the first concentrated solution into an iron gathering system to prepare iron gathering;
filtering and separating prewashed white water generated by prewashing a plate washing frame to obtain a second clear liquid and a second concentrated liquid, sending the second clear liquid into an acidolysis leaching system to serve as make-up water of the acidolysis leaching system, and sending the second concentrated liquid into a polyferric system to prepare polyferric;
filtering and separating first washing white water generated by washing a first washing plate frame to obtain third clear liquid and third concentrated liquid, sending the third clear liquid into a second washing plate frame to be used as washing water of the second washing plate frame, and sending the third concentrated liquid into the first washing plate frame to be used as pre-washing water of the first washing plate frame;
the method comprises the following steps of (1) filtering and separating prewashed white water generated by prewashing a plate washing frame to obtain a second clear liquid and a second concentrated liquid, wherein the second clear liquid and the second concentrated liquid specifically comprise:
carrying out solid-liquid separation on pre-washing white water generated by pre-washing a plate washing frame, and removing powder in the pre-washing white water to obtain pre-washing white water clear liquid;
and performing ion separation on the prewashed white water clear liquid generated by solid-liquid separation to obtain the second clear liquid and the second concentrated solution.
6. The method for recycling waste acid and white water of titanium dioxide produced by a sulfuric acid process according to claim 5, wherein the step of treating the waste acid produced by filtering a plate washing frame to obtain ferrous sulfate monohydrate, 70 acid and condensed water specifically comprises the steps of:
pretreating waste acid generated by filtering a plate washing frame, removing powder in the waste acid to obtain fourth clear liquid, and returning the powder to the plate washing frame for water washing;
spraying and concentrating the fourth clear liquid by using calcination tail gas;
filtering the fourth clear liquid after spray concentration to remove powder and a small amount of crystalline ferrous sulfate in the fourth clear liquid after concentration;
and evaporating the fourth clear liquid after filtering treatment to obtain 70 acid, ferrous sulfate monohydrate and condensed water, sending the 70 acid into an acidolysis leaching system to be used as acidolysis acid of an acidolysis section, and sending the condensed water into a plate washing frame to be used as washing water make-up water.
7. The method for recycling waste acid and white water of titanium dioxide produced by a sulfuric acid process according to claim 6, further comprising:
performing solid-liquid separation on a part of waste acid generated by filtering the plate washing frame, removing powder in the waste acid, and returning the powder to the plate washing frame for water washing;
and feeding the fifth clear liquid into a polyferric system to prepare the polyferric.
8. The recycling method of waste acid and white water of titanium dioxide by a sulfuric acid process according to claim 5, wherein the filtering and separating treatment of acid water generated by pre-washing a plate washing frame to obtain a first clear solution and a first concentrated solution specifically comprises:
carrying out solid-liquid separation on acid water generated by prewashing a plate washing frame, and removing powder in the acid water to obtain acid water clear liquid;
carrying out ion separation on acid water clear liquid generated by solid-liquid separation to obtain the first clear liquid and the first concentrated solution;
the filtration and separation treatment of the white washing water generated by washing the plate frame to obtain the third clear liquid and the third concentrated liquid specifically comprises the following steps:
carrying out solid-liquid separation on white washing water generated by washing a plate washing frame to remove powder in the white washing water to obtain white washing water clear liquid;
and carrying out ion separation on a white washing water clear solution generated by solid-liquid separation to obtain the third clear solution and the third concentrated solution.
9. The method for recycling waste acid and white water of titanium dioxide produced by a sulfuric acid process according to claim 8, further comprising:
and returning powder generated by solid-liquid separation of the acid water, powder generated by solid-liquid separation of the prewashing white water and powder generated by solid-liquid separation of the prewashing white water to a plate washing frame for water washing.
10. The recycling method of waste acid and white water of titanium dioxide by sulfuric acid process according to claim 5,
the content of iron ions in the first clear liquid is less than 5000ppm, and the content of iron ions in the first concentrated solution is more than 50000ppm;
the content of iron ions in the second clear liquid is less than 500ppm, and the content of iron ions in the second concentrated solution is more than 50000ppm;
the iron ion content in the third clear liquid is less than 2ppm.
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