CN204434301U - Metallurgy industry sintering machine head end electro-precipitating dust extracts the equipment of sylvite - Google Patents

Abstract

The utility model relates to a device for extracting potassium salt from electric dust removal ash of a sintering machine head in the metallurgical industry. The equipment includes a sintered ash leaching tank which is connected in turn to a first-stage filter press unit, a rich liquid storage tank, a chemical precipitation tank, a mechanical centrifugal separation unit, and an evaporation crystallization unit. The utility model uses industrial water to directly leach and extract potassium salt from electric dust removal ash; the chemical method makes impurity metal ions in the leaching solution quickly and stably form precipitation, and the product has higher purity; mechanical centrifugal separation is used to carry out the precipitation of the precipitated solution. High-efficiency separation; adding industrial water and condensed water returned by the evaporation and crystallization unit to leach the filter residue twice, and return the poor liquid produced by the secondary pressure filtration and centrifugal separation unit as the sintering ash leaching solution, which not only ensures the sintering ash The maximum extraction of medium potassium salt also ensures the reasonable distribution of the leach solution in the whole system, and no waste water is discharged. The utility model has the advantages of simple structure, economy and reliability, and can obtain high-purity potassium salt product after evaporation, crystallization and drying.

Description

Equipment for extracting potassium salt from electric dust removal ash of sintering head in metallurgical industry

technical field

The utility model belongs to the technical field of comprehensive utilization of solid waste resources, and also belongs to the technical field of chemical production, in particular to a device for extracting potassium salt from electric dust removal ash of a sintering machine head in the metallurgical industry.

Background technique

The metallurgical industry is an important pillar industry of my country's rapid economic development, but it is also one of the industries with high energy consumption and high pollution. Among them, a large amount of dust generated during the sintering process is one of the main sources of pollution in the metallurgical industry. According to statistics, the electric dust removal ash (sintered ash for short) of sintering head produced in my country every year is as high as 15 million tons, which contains a large amount of iron, calcium, silicon, carbon, potassium, sodium, chlorine and other elements, and also contains a small amount of lead. , zinc, copper and other heavy metal elements. Therefore, how to properly dispose of sinter ash and rationally utilize its effective resources is of great significance to environmental protection and sustainable development of the metallurgical industry.

Since sintered ash is rich in water-soluble potassium and sodium salts and harmful heavy metal elements, it is not suitable to be stockpiled or landfilled. At present, for the comprehensive treatment of sinter ash, most domestic metallurgical industries return it directly to the original process for re-batching and sintering to recycle useful elements such as iron and residual carbon contained in it. Although this method realizes the treatment and resource utilization of sinter ash to a certain extent, in the process of continuous circulation back to sintering, harmful elements such as potassium, sodium, zinc, and lead contained in sinter ash will be continuously enriched. In particular, the enrichment of alkali metal elements such as potassium and sodium will not only cause corrosion and damage to the blast furnace body and auxiliary equipment, seriously affect the normal operation of the original process, but also reduce the dust removal efficiency and operational stability of the electrostatic precipitator. At the same time, direct return to sintering also causes waste of resources of some metal elements. Therefore, more and more attention has been paid to how to utilize sinter ash as a resource more reasonably.

Detection and analysis show that the sintered electrostatic precipitator ash contains more potassium elements, which exist in the form of potassium chloride and potassium sulfate. China, as a large agricultural country, lacks and unevenly distributes potassium fertilizer resources, and needs to import a large amount. Therefore, extracting potassium salt from sintered ash can not only effectively solve the problem that the enrichment of alkali metals will have an adverse effect on the normal operation of metallurgical processes, but also effectively alleviate the current situation of potassium fertilizer shortage in my country, which has important significance and broad prospects.

Patent CN101428832 discloses a method for extracting potassium sulfate from sintering dust and its preparation. This invention adopts the method of soaking at room temperature for 3 days to extract potassium sulfate from sintering dust removal ash, which takes a long time and has low extraction efficiency; in addition, the method improves the crystallization yield of potassium sulfate by adding a large amount of organic solvent formamide, However, no effective measures have been taken to remove other impurity metal ions contained in the leachate, so as to affect the purity of the finally obtained potassium sulfate product.

In addition, CN101234766 discloses a method for producing potassium chloride by using sintered electrostatic precipitator ash in iron and steel plants. This method uses vibration leaching, and achieves solid-liquid separation by natural sedimentation, which takes a long time and is inefficient, especially for sintered ash with a small particle size, it is difficult to achieve efficient solid-liquid separation; in addition, the invention It takes a long time to adopt slow cooling and fractional crystallization.

Contents of the invention

The purpose of this utility model is to provide a kind of equipment for extracting potassium salt from the electric dust removal dust of the sintering machine head in the metallurgical industry, so as to solve the problem of alkali metal elements such as potassium and sodium contained in the existing process when the sintering ash returns to the sintering process. Enrichment will have a serious adverse effect on the original process, and at the same time make the extracted potassium salt meet the requirements of agricultural supplies, and alleviate the current situation of shortage of potassium salt in our country.

The purpose of this utility model is achieved through the following technical solutions: Potassium element exists in forms such as potassium chloride and potassium sulfate in the sintering machine head electric dust removal ash, and adopts directly adding water to dissolve, and the potassium salt in the sintering ash can be dissolved into the liquid phase. However, during the dissolution process, iron, calcium, magnesium, copper, zinc, aluminum, manganese, lead and other metal elements contained in the sintered ash will also partially dissolve into the liquid phase to form Fe ³⁺ , Ca ²⁺ , Mg ²⁺ , Cu ²⁺ , Zn ²⁺ , Al ³⁺ , Mn ²⁺ , Pb ²⁺ , etc. Therefore, in order to efficiently remove insoluble components and impurity metal ions in the sintered ash leach solution and obtain high-purity potassium salt, the utility model adopts operations such as stirring leaching, chemical precipitation, mechanical centrifugal separation, and evaporation crystallization. Among them, the chemical precipitation operation is realized by adding alkaline substances or sulfides such as potassium hydroxide and potassium carbonate, and the mechanical centrifugal separation unit is a horizontal screw discharge sedimentation centrifuge.

A kind of equipment for extracting potassium salt from electric dust removal ash of sintering head in the metallurgical industry. The sintering ash leaching tank is connected with a first-stage filter press unit, a rich liquid storage tank, a chemical precipitation tank, a mechanical centrifugal separation unit, and an evaporation crystallization unit in sequence.

The primary filter press unit is also connected to a filter residue leaching tank, and the filter residue leaching tank is connected to a secondary filter press unit.

The mechanical centrifugal separation unit is a horizontal screw discharge sedimentation centrifuge.

The method for leaching, separating and purifying potassium salt by using the above-mentioned equipment to sinter ash comprises the following steps.

(1) Add industrial water and leach the sintered ash under stirring conditions. After the leaching is completed, the formed suspension is sent to the first-stage filter press unit for solid-liquid separation; The rich solution enters the rich solution storage tank, while the filter cake enters the filter residue leaching tank for leaching again.

(2) After the filter cake is stirred and leached in the filter residue leaching tank, it is pumped to the secondary filter press unit for filtration. The resulting filter residue is dried and directly returned to the original process for re-batching and sintering, while the filtrate is Return to the sintered ash leaching tank, used as leaching solution for sintered ash.

(3) After the rich liquid stored in the rich liquid storage tank is transferred to the chemical precipitation tank by a pump, alkaline substances such as potassium hydroxide and potassium carbonate are added to adjust the pH value of the rich liquid in the chemical precipitation tank to 8~9 ; At this point, the following reaction will take place in the solution:

Fe ³⁺ + 3OH ^- = Fe(OH) ₃ ↓

Cu ²⁺ + 2OH ^- = Cu(OH) ₂ ↓

Al ³⁺ + 3OH ^- = Al(OH) ₃ ↓

Zn ²⁺ + 2OH ^- = Zn (OH) ₂ ↓

Mn ²⁺ + 2OH ^- = Mn (OH) ₂ ↓

Pb ²⁺ + 2OH ^- = Pb(OH) ₂ ↓

After the pH value is adjusted to 8~9, most of the impurity metal ions in the solution can enter the solid phase through reaction to form precipitates.

(4) After the pH adjustment is completed, the solution is sent to the mechanical centrifugal separation unit for precipitation removal.

(5) Through the function of the horizontal screw discharge sedimentation centrifuge in the mechanical centrifugal separation unit, insoluble components such as metal hydroxide precipitation in the solution can be separated efficiently, even for particles with small particle sizes, effective separation can be achieved .

(6) After solid-liquid separation, the rich liquid rich in potassium salt enters the subsequent evaporation and crystallization unit for the production of potassium salt; the filter residue generated during the centrifugation process enters the filter residue leaching tank for leaching again to extract It may still contain small amounts of potassium salts.

The beneficial effects of the utility model are: using industrial water to directly leach potassium salt from the electrostatic precipitator ash of the sintering machine head, and adopting the method of mechanical separation to separate the solid-liquid from the suspension formed after leaching, which is better than that adopted in the patent CN101234766 It is more efficient and feasible to carry out solid-liquid separation in the way of natural sedimentation; the impurity metal ions in the leaching solution can quickly and stably form precipitation and enter the solid phase through chemical methods. Compared with the final product obtained in the patent CN101234766, the impurity metal elements less, the product purity is higher; at the same time, a horizontal spiral discharge sedimentation centrifuge is used to carry out efficient solid-liquid separation of the precipitated solution, even for particles with small particle sizes, effective separation can be achieved; in addition, in the present invention , the filter residue is leached twice by adding industrial water and the condensed water returned by the evaporation and crystallization unit, and returning the poor liquid produced by the second-stage filter press and centrifugal separation unit as the sintering ash leaching liquid, which not only ensures the sintering ash The maximum extraction of potassium salt also ensures the reasonable distribution of the leach solution in the whole system, and no waste water is discharged. The entire leaching and separation device has a simple structure, is economical and reliable, and can efficiently extract and separate the potassium salt in the sintered ash. After drying through evaporation and crystallization, a high-purity potassium salt product can be obtained, which is an effective solution to the current shortage of potassium salt in my country. Both the problem of adverse effects and the enrichment of alkali metals are positive.

Description of drawings

Fig. 1 is the equipment diagram of the present utility model.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described further.

A kind of equipment for extracting potassium salt from electric dust removal ash of sintering head in the metallurgical industry. The sintering ash leaching tank is connected with a first-stage filter press unit, a rich liquid storage tank, a chemical precipitation tank, a mechanical centrifugal separation unit, and an evaporation crystallization unit in sequence.

The primary filter press unit is also connected to a filter residue leaching tank, and the filter residue leaching tank is connected to a secondary filter press unit.

The mechanical centrifugal separation unit is a horizontal screw discharge sedimentation centrifuge.

The invention discloses a method for extracting potassium salt from electric dust of sintering head in the metallurgical industry, the steps comprising: stirring and leaching, chemical precipitation, mechanical centrifugal separation and evaporation crystallization.

The stirring and leaching step comprises:

(1) Add industrial water and leach the sintered ash under stirring conditions. After the leaching is completed, the formed suspension is sent to the first-stage filter press unit for solid-liquid separation; The rich solution enters the rich solution storage tank, while the filter cake enters the filter residue leaching tank for releaching;

(2) After the filter cake is stirred and leached in the filter residue leaching tank, it is pumped to the secondary filter press unit for filtration, and the resulting filter residue is dried and directly returned to the original sintering process for re-batching and sintering, while the filtrate It returns to the sintered ash leaching tank and is used as a leaching solution for the sintered ash.

Described chemical precipitation step comprises:

(3) After the rich liquid stored in the rich liquid storage tank is transferred to the chemical precipitation tank by a pump, alkaline substances such as potassium hydroxide and potassium carbonate are added to adjust the pH value of the rich liquid in the chemical precipitation tank to 8~9 ;A chemical precipitation reaction occurs in the solution: the impurity metal ions in the solution form a precipitate through the reaction and enter the solid phase;

(4) After the pH adjustment is completed, the solution is sent to the mechanical centrifugal separation unit.

Described mechanical centrifugation step comprises:

(5) The solution delivered to the mechanical centrifugal separation unit is separated from the insoluble components in the solution through the horizontal screw discharge sedimentation centrifuge in the mechanical centrifugal separation unit. The solid insoluble components are filter residues, and the liquid state is a rich solution rich in potassium salts. The ingredients are metal hydroxide precipitates.

The evaporative crystallization step comprises:

(6) After solid-liquid separation, the rich liquid rich in potassium salt enters the evaporation crystallization unit for the production of potassium salt.

The filter residue produced in the mechanical centrifugal separation step (5) enters the filter residue leaching tank for leaching again.

In the above steps (1) and (2), after the sintered ash is stored in the sintered ash bin, it is transported to the sintered ash leaching tank, and industrial water is added, and the leaching is carried out under the condition of stirring. Water is added to the ash leaching tank. After the whole system operates normally, there is no need to add new industrial water. Instead, the lean liquid returned by the secondary filter press unit and centrifugal separation unit is used as the leaching liquid for sintered ash.

In the above steps (1) and (2), after the sintered ash leaching is completed, the suspension in the sintered ash leaching tank is transported to the first-stage filter press unit for solid-liquid separation; after separation, the rich solution rich in potassium salt It enters the rich liquid storage tank for storage and is used for subsequent separation and purification; while the filter cake is transferred to the filter residue leaching tank, where industrial water is added, and stirring and leaching are performed again. the

After the leaching in the filter residue leaching tank is completed, the solution in it is transported to the secondary filter press unit for solid-liquid separation; after separation, the solid residue is obtained, which is rich in iron elements, and after drying, it directly returns to the original process for re-batching and sintering; The filtrate may still contain a small amount of soluble salts such as potassium salt, and it is directly returned to the sintered ash leaching tank as the leaching solution of the sintered ash.

In the above steps (3) and (4), the rich liquid in the rich liquid storage tank is transported to the chemical precipitation tank, and the pH value of the solution is adjusted to 8~ by adding alkaline substances such as potassium hydroxide and potassium carbonate. 9. In this step, the pH value is adjusted to 8-9, and the pH value at which some metal ions are completely precipitated is slightly higher than this pH value range. Therefore, after most of the metal ions are precipitated, there will still be some metal ions in the solution that cannot completely form hydroxide precipitation and be removed, mainly Mn ²⁺ , Mg ²⁺ , Pb ²⁺ , etc. Add a small amount of sulfide to the chemical precipitation tank to further remove these metal ions. The main reactions in this step are:

Mn ²⁺ + S ^2- = MnS↓

Mg ²⁺ + S ^2- = CuS↓

Pb ²⁺ + S ²⁻ = PbS ↓.

After the precipitation is completed, the solution in the chemical precipitation tank is transported to the mechanical centrifugal separation unit to separate and remove the metal precipitation.

In the above step (5), the separation device used is a horizontal screw discharge sedimentation centrifuge. Through its centrifugal separation, insoluble components such as metal hydroxide precipitation in the solution can be separated efficiently, even for particles with small particle sizes. , can also achieve effective separation, so as to obtain high-purity potassium salt solution.

The solid slag separated by the horizontal screw discharge sedimentation centrifuge, mainly metal precipitates, is directly returned to the filter residue leaching tank, and is leached again together with the filter cake separated from the first-stage filter press unit to extract the possible impurities contained in it. Small amounts of potassium salts.

The potassium salt solution from which impurity metal ions have been removed enters the evaporation crystallization unit for concentration and crystallization, and the concentrated potassium salt solution enters the subsequent centrifugal separation and drying unit to produce potassium salt products. In this step, the condensed water produced by the evaporation and crystallization unit is returned to the filter residue leaching tank to be used as the filter residue leaching liquid, while the lean liquid produced in the centrifugation is returned to the sintering ash leaching tank to be used as the sintering ash leaching liquid.

Claims (3)

1. from metallurgy industry sintering machine head end electro-precipitating dust, extract an equipment for sylvite, it is characterized in that sintering ash leaching pond connects one-level press filtration unit, rich solution bin, chemical precipitation tank, emchanically centrifugal separation unit, evaporative crystallization unit successively.

2. a kind of equipment extracting sylvite from metallurgy industry sintering machine head end electro-precipitating dust as claimed in claim 1, it is characterized in that one-level press filtration unit also connects filter residue and leaches pond, filter residue leaches pond and connects secondary press filtration unit.

3. a kind of equipment extracting sylvite from metallurgy industry sintering machine head end electro-precipitating dust as claimed in claim 1, is characterized in that emchanically centrifugal separation unit is horizontal spiral discharge sedimentation centrifuge.