阅读说明：本技术 一种从烧结灰中提取硫酸钾、氯化钠的方法 (Method for extracting potassium sulfate and sodium chloride from sintering ash ) 是由 尚方毓 荆小兵 李媛 张婧 于 2020-06-17 设计创作，主要内容包括：本发明属于钢厂资源再利用领域,主要涉及钢厂烧结灰中钾元素提取及转化。本技术方案：在热水中加入定量的烧结灰,搅拌过滤除去水不溶物,滤液用碱调节PH、活性炭脱色后再次过滤。根据滤液里面K～(+),Na～(+),Cl～(-),SO-(4)～(2-)组成进行蒸发浓缩。将浓缩液体分成两份,其中一份里加入工业元明粉转化反应,过滤分离出钾芒硝和盐母液,盐母液蒸发后析出氯化钠。然后将钾芒硝加入到另一份浓缩液再次转化反应,过滤分离出硫酸钾和钾母液。反应方程如下：6KCl+4Na-(2)SO-(4)=Na-(2)SO-(4)·3K-(2)SO-(4)+6NaCl、2KCl+Na-(2)SO-(4)·3K-(2)SO-(4)=4K-(2)SO-(4)+2NaCl过滤出来的硫酸钾、氯化钠经过干燥可得产品。(The invention belongs to the field of steel mill resource recycling, and mainly relates to extraction and conversion of potassium element in steel mill sintering ash. The technical scheme is as follows: adding a certain amount of sintering ash into hot water, stirring, filtering to remove water insoluble substances, adjusting the pH of the filtrate with alkali, decolorizing with active carbon, and filtering again. According to the content K in the filtrate + ,Na + ,Cl ‑ ,SO 4 2‑ The composition was concentrated by evaporation. Dividing the concentrated liquid into two parts, adding industrial anhydrous sodium sulphate into one part, performing conversion reaction, filtering to separate out glaserite and salt mother liquor, and evaporating the salt mother liquor to separate out sodium chloride. Adding another part of concentrated solution into the glaserite for conversion reaction again, and filtering to separate potassium sulfate and potassium mother liquor. The reaction equation is as follows：6KCl+4Na 2 SO 4 =Na 2 SO 4 ·3K 2 SO 4 +6NaCl、2KCl+Na 2 SO 4 ·3K 2 SO 4 =4K 2 SO 4 And (6) drying potassium sulfate and sodium chloride filtered by +2NaCl to obtain the product.)

1. A method for extracting potassium sulfate and sodium chloride from sintering ash comprises the following steps of (1) weighing 1 part by weight of dedusting ash, adding 2-5 times of water by weight of the dedusting ash, and heating and boiling; (2) filtering the solid-liquid mixture, and adding alkali into the filtrate to adjust the pH value of the solution so as to precipitate the rest metal ions (such as calcium, iron, magnesium and the like) in the water; (3) adding a decoloring agent to decolor the liquid for 3-5 hours; (4) filtering the decolorized liquid, and performing reduced pressure evaporation concentration on the obtained filtrate in an evaporator until the potassium ions are 160-180 g/L; (5) dividing the concentrated solution into two parts, adding a certain amount of industrial anhydrous sodium sulphate into one part, converting to form glaserite precipitate, and evaporating the separated salt mother liquor at 100-150 ℃ to separate out industrial sodium chloride by multiple effects; (6) adding the glaserite and the other part of concentrated solution into a reaction kettle for double decomposition reaction to convert the glaserite into potassium sulfate precipitate, and filtering and separating to obtain wet potassium sulfate and a potassium mother solution; mixing the potassium mother liquor and the salt mother liquor, adding a proper amount of industrial anhydrous sodium sulphate to prepare the glaserite again, and circulating the steps; (7) the wet potassium sulfate is dried by hot air to obtain the product.

2. The method for extracting potassium sulfate from sintered ash as claimed in claim 1, wherein the alkali in step (2) is selected from sodium sulfide and sodium carbonate, but not limited thereto.

3. The method for extracting potassium sulfate from sintered ash as claimed in claim 1, wherein the decoloring in step (3) is performed by using activated carbon, diatomaceous earth, resin, etc., but not limited thereto.

4. The method of claim 1, wherein the grade of the technical anhydrous sodium sulfate in step (5) is preferably 2 or more, and the ratio of potassium in the mixed solution is potassium: sodium =1:0.69 to 0.70 (molar ratio).

Technical Field

The invention belongs to the field of chemical product manufacturing, and particularly relates to potassium sulfate and sodium chloride extracted from sintered dedusting ash and a preparation method thereof. The production process includes soaking the dissolved matter in dedusting ash in water, filtering and separating, pre-treatment of the filtrate with anhydrous sodium sulfate to form glaserite precipitate, separating glaserite, and converting the separated glaserite solution with the other treated solution to produce potassium sulfate. The filtered mother liquor is evaporated, concentrated and separated out industrial salt sodium chloride, and the mother liquor returns to the previous conversion system for recycling.

Background

The steel industry is the backbone industry of China, and plays an important role in national economy, and China is the biggest steel industry country in the world. However, the steel industry is also the most prominent industry with serious energy consumption and environmental pollution, and with the increasing execution of the national environmental protection policy, the steel industry produces a large amount of dust removal ash to be centrally stacked every year, pollutes the environment and urgently needs treatment, so that the comprehensive utilization of the dust removal ash resources is imperative.

Sintering production is an important step for preparing raw materials of iron and steel enterprises, and the main purpose of the sintering production is to fully utilize ore resources, meet the development of the iron and steel industry and reduce the cost. At present, dust removal ash in the steel industry is actively researched and utilized in all countries, but most of the dust removal ash is concentrated in low-added-value industries such as concrete, slag wool and the like, and the resource utilization rate is low. Through preliminary analysis to the dust removal ash of steel and iron works, the main component of dust removal ash is that forms such as chlorides, the sulphate of metal element such as potassium, sodium exist, also exist other simultaneously if: lead, manganese, calcium, magnesium, zinc and other elements which have certain harm to steel smelting can be returned to a smelting system only by removing dust. In China, the distribution of potassium salts is concentrated in Qinghai and other places, and potassium deficiency is also acute in inland, so that the resource utilization prospect is very wide.

CN101234766 discloses a method for producing potassium chloride by using sintering dust removed from steel works. The potassium chloride and the sodium chloride are extracted by adopting a fractional cooling crystallization method, the purity can reach 95-98%, and the total amount of calcium and magnesium is 0.4-3%. However, potassium chloride easily causes soil hardening, and many plants are not chlorine-resistant, so that the application of potassium chloride is limited. CN101428832 discloses a method for extracting potassium sulfate from fly ash. It adds ammonium sulfate into water soluble matter and produces potassium sulfate with organic solvent formamide. The process needs to recover the organic solvent, and the process is correspondingly complex. The invention adopts the anhydrous sodium sulphate as an auxiliary material, has convenient source and simple production process, does not use organic solvent, has wider application of extracting the potassium sulfate in agriculture than potassium chloride, and accords with the quality standard of GB/T20406-.

Disclosure of Invention

The invention mainly aims at potassium and sodium salts in sintered ash, provides an economical and feasible treatment method for extracting potassium sulfate and sodium chloride from the sintered ash, and fundamentally solves the problems of long-term stacking of the fly ash and waste of valuable resources. The method for preparing potassium sulfate and sodium chloride comprises the steps of dissolving, removing impurities, decoloring, evaporating, performing double decomposition, crystallizing, filtering, drying and the like.

The technical scheme of the invention is as follows: the technical scheme for extracting potassium sulfate and sodium chloride from the sintering ash is provided, and the further preferable technical scheme or technical characteristics comprise the following steps: (1) weighing 1 part of dedusting ash by weight, adding water which is 2-5 times of the dedusting ash by weight, and heating and boiling; (2) filtering the mixture obtained in step (1), adding alkali into the filtrate to precipitate the rest metal ions (such as calcium, magnesium, lead, manganese, etc.) in water; (3) decoloring the liquid obtained in the step (2) for 3 hours, and then filtering; (4) carrying out reduced pressure concentration on the filtrate obtained in the step (3) in multi-effect evaporation; (5) and (4) analyzing the components of the filtrate and dividing the filtrate into two parts, adding industrial anhydrous sodium sulphate in a certain proportion into one part of the concentrated solution according to the amount of sodium element in the filtrate, controlling the temperature at 25 ℃, reacting for 60-80 min to form glaserite precipitate (the process is conversion), and evaporating the separated mother solution at 100 ℃ by multiple effects to separate out industrial sodium chloride.

(1) Adding the glaserite and the other part of concentrated solution into a reaction kettle for double decomposition reaction, controlling the temperature at 25 ℃ and the reaction time at 30-60 min, and filtering to obtain wet potassium sulfate (the process is secondary conversion); (2) drying wet potassium sulfate with hot air to obtain the product; (3) mixing the mother liquor separated in the first conversion step and the second conversion step with the concentrated solution for conversion and recycling; (4) by analyzing the content of potassium and sodium elements in the filter residue in the step (2), the extraction rate of the potassium and sodium elements in the process can be known to be 90-97%.

The method utilizes potassium and sodium element resources in metallurgical dedusting ash, adopts a simple process and fully combines the rich anhydrous sodium sulphate resources in China to extract potassium sulphate which is urgently needed by agriculture in China, not only improves the resource utilization rate, but also protects the environment, and has better economic, environmental and social benefits. Inorganic salt is adopted for treatment in the whole process, so that the use and the recovery of an organic solvent are avoided, and the danger in the production process is reduced.

Drawings

FIG. 1 is a flow chart of the process for extracting potassium sulfate and sodium chloride.

Detailed Description

The present invention is further illustrated by, but not limited to, the following examples. The dust removal ash used in the embodiment is dust removal ash of a sintering machine head, and the main components of the dust removal ash are TFe: 12.45%, K₂O：13.884%， Na₂O：2.439% ，Pb：2.648%， CaO：1.73%， S：0.788%， Al₂O₃: 0.61%, MgO: 0.47%, Cu: 0.141%, Zn: 0.421 percent. The aqueous solution after being treated by the pretreatment system comprises the following components: 17.3 to 22.5 percent of potassium salt (calculated by potassium oxide), 1.1 to 3.5 percent of sodium salt (calculated by sodium oxide), 24.2 to 35.5 percent of chloride salt (calculated by chlorine) and 1.5 to 3.2 percent of sulfate (calculated by sulfate radical)

Example 1: 300g of solid dedusting ash is slowly added into 1200mL of hot water, stirring and heating are continuously carried out for boiling, stirring is continuously carried out for 60 minutes after the addition is finished, then a small amount of sodium sulfide solution is added into the filtrate to enable the solution to have pH =8, then water insoluble matters are filtered and removed to obtain 1155.35g of filtrate weight, 0.5g of activated carbon is added into the filtrate to be kept stand for 180 minutes, and after filtration, reduced pressure evaporation is carried out until the filtrate weight is 301 g. Adding 43.65g of industrial anhydrous sodium sulfate into 120g of filtrate, controlling the temperature at 25 ℃, reacting for 80 min, separating 30.84g of wet glaserite and 132.81g of mother liquor (the process is conversion), and separating 17.17g of sodium chloride (dry basis) by four-effect evaporation of the mother liquor at 100 ℃. Adding the separated wet glaserite into another 181g of the concentrated solution, reacting at 25 deg.C for 40 min, separating to obtain wet potassium sulfate (second conversion), and oven drying to obtain 48.95 g.

Example 2: 1000g of solid dedusting ash is slowly added into 4000mL of hot water, stirring and heating are continuously carried out for boiling, stirring is continuously carried out for 60 minutes after the addition is finished, then a small amount of sodium hydroxide solution is added into the filtrate to enable the pH of the solution to be =7, then water insoluble matters are filtered and removed to obtain 3855.35g of filtrate weight, 1.5g of activated carbon is added into the filtrate to be kept stand for 180 minutes, and the mixture is filtered and evaporated under reduced pressure until the filtrate weight is 1031 g. Adding 143.65g of industrial anhydrous sodium sulphate into 450g of filtrate, controlling the temperature at 25 ℃, reacting for 80 min, separating 120.84g of wet glaserite and 472.81g of mother liquor (the process is conversion), and evaporating 93.17g of sodium chloride (dry basis) by multiple effects at 100 ℃. Adding the separated wet glaserite into another part 581g of concentrated solution, reacting at 25 deg.C for 40 min, separating to obtain wet potassium sulfate (second conversion), and oven drying to obtain 160.48 g.

The results of the test data of the two embodiments are shown in Table I

TABLE one example 1-2 test data

While in the foregoing description numerous specific details have been set forth to provide a thorough understanding of the present invention, the foregoing description is merely a specific process of the invention, which can be embodied in many different forms and should not be construed as limiting the invention to the specific embodiments disclosed above. Any simple modification, equivalent change and modification, or partial replacement of the above-described embodiments by those skilled in the art without departing from the technical spirit of the present invention should be covered within the scope of the claims of the present invention.