CN102703689A - Process method for extracting and separating iron from industrial waste iron mud and preparing iron oxide red - Google Patents

Abstract

The invention discloses a process method for extracting and separating iron from industrial waste iron mud and preparing iron oxide red and relates to a chemical engineering separation method. The process method disclosed by the invention is of a new process for extracting and separating the iron from the industrial waste iron mud and preparing the iron oxide red; the process method comprises four technical operations, and the chemical engineering purpose of not only extracting and separating the iron, but also preparing a high-added value product, namely the iron oxide red; and the four technical operations are respectively as follows: (1) a dilute sulfuric acid-dilute hydrochloric acid mixed acid leaching process of the industrial waste iron mud and an acid leaching solution reduction process; (2) the process for preparing the iron oxide red by enabling a ferrous sulfate solution to react with a carbonate and performing oxidizing roasting on a precipitate intermediate; (3) the process for preparing ammonia sulfate by crystallizing a precipitation solution under the action of an organic solvent; and (4) the process for recovering the organic solvent by evaporation and preparing ammonium chloride by evaporation. The process method disclosed by the invention is suitable for extracting and separating iron element from various iron-containing minerals and industrial waste slag, and by using the process method, valuable components can be comprehensively utilized, and environmental pollution and the waste of resources can be reduced.

Description

A process for extracting and separating iron from industrial waste iron sludge and preparing iron red

technical field

The invention relates to a chemical separation method, in particular to a process for extracting and separating iron from industrial waste iron sludge and preparing iron red.

Background technique

With the development of the chemical industry, the global environment continues to deteriorate, and environmental protection has become the focus of the governments of all countries. Reducing the discharge of three wastes, waste treatment and secondary utilization are common methods to solve environmental problems in the chemical industry.

Iron powder is a commonly used reducing agent. After oxidation, it is discharged as waste in large quantities. Because it looks like black mud, it is commonly called iron mud. The manufacturers that produce iron sludge are mainly dye factories, pharmaceutical factories and chemical factories. Taking iron filings to reduce nitrobenzene to o-toluidine as an example, based on an annual output of 1,000 tons of o-toluidine, at least 1,500 tons of iron sludge will be produced; using iron powder to reduce violin acid, based on an annual output of 800 tons , about 1000t of waste iron sludge is discharged every year.

Iron sludge is mostly treated by stockpiling, land burial or sending it to steel plants for recycling. Stockpiling is the simplest method, but it takes up a lot of land, and long-term stockpiling is easy to generate dust and pollute the air; landfill not only takes up a lot of land, but also often causes underground water sources, rivers, mountains and rivers to 1. The lake is polluted, causing secondary pollution; sending it to the iron and steel plant for recycling can reduce the amount of landfill and save land, but because of its fine particle size, it is easy to block the iron-making furnace during recycling, which deteriorates the operating conditions of iron-making and seriously reduces the quality of products . At present, most recycling methods have problems such as low utilization rate and secondary pollution.

Developed countries carried out the treatment of iron-containing waste in the 1940s and 1950s. Over the past ten years, foreign dye factories have realized the problems caused by the large amount of iron sludge produced by this process, so they have fundamentally changed the production process of amine-based dyes, such as the use of catalytic hydrogenation reduction, electrocatalytic hydrogenation, zinc On the other hand, most of the dyeing and chemical enterprises are transferred to China or other third world countries. Due to the relatively backward production technology and equipment in our country, most of the dyeing and chemical factories still use iron powder reduction. Therefore, the existence of iron slime in our country is long-term, and the degree of its comprehensive utilization and technical level will affect the survival and efficiency of dyestuffs and other factories, as well as the environmental protection and sustainable development of our country. At present, the comprehensive utilization processes of industrial waste iron sludge mainly include the following types:

1. Supercritical technology

Using supercritical technology (SCWO) to pretreat iron slime, the quality of iron red obtained after calcining is obviously better than that of iron slime directly calcined. The advantage of this method is that the process is simple and the product quality is good. The disadvantage is that the water needs to be in a supercritical state and the operating conditions are high.

2. Production of polyferric sulfate from iron mud

Polyferric sulfate is an inorganic water purifier. It has strong mixing ability, less dosage, good water quality after treatment, non-toxic and so on. Use iron mud as raw material to prepare FeSO ₄ solution by crushing and acid leaching, neutralize it with NaOH to convert it into Fe(OH) ₂ , and then undergo oxidation, telomerization, solidification, and crushing to obtain the finished product of polymerized ferric sulfate . Advantages: Ferric polysulfate is a high value-added product, which makes full use of iron resources in waste by using iron slime as raw material. Disadvantages: The process route is longer.

3. Dry method

The black iron sludge waste from the dye industry is sun-dried or dried to volatilize a small amount of oily components in the iron sludge waste, and sent to ∮ 1.5×24 rotary kiln for calcination with heavy oil or coal. Calcination temperature: 250 ^o C ~ 350 ^o C at the kiln tail, 800 ^o C ~ 850 ^o C at the kiln head. After calcining, the material is sent to a Raymond pulverizer for superfine pulverization to obtain iron oxide red pigment.

In addition, improvements were made to the dry method. Adding sulfuric acid as an oxidizing agent to raw iron slime, it was directly put into a muffle furnace to calcinate the finished iron oxide red product, and the influence of the calcining temperature was investigated, and the calcining temperature for preparing iron oxide dyes by the dry method of iron mud was preferably 800 ^o C. The process of this method is simple, but the obtained iron red has low iron content and poor quality. The advantage of this method is that the process is simple. The disadvantage is that the quality of the obtained iron red is low, and the exhaust gas needs to be treated.

Contents of the invention

The object of the present invention is to provide a process for extracting and separating iron from industrial waste iron sludge and preparing iron red. The invention proposes a new process of leaching waste iron sludge with mixed acid of industrial waste sulfuric acid and hydrochloric acid, reacting the acid leaching solution with carbonate to prepare iron red intermediate, and roasting the intermediate to prepare iron oxide red. The advantageous effects of technology, economy and easy realization of industrialized production are realized.

The purpose of the present invention is achieved through the following technical solutions:

A process for extracting and separating iron from industrial waste iron sludge and preparing iron red, the method includes the following processes: the sulfuric acid and hydrochloric acid mixed acid leaching of industrial waste iron sludge and the Fe3 ⁺ reduction process of acid leaching solution; ferrous sulfate The process of preparing iron oxide red by reacting the solution with carbonate and oxidizing and roasting the precipitate intermediate; the process of preparing ammonium sulfate by crystallizing the precipitation liquid with an organic solvent; the process of evaporating and recovering the organic solvent and preparing ammonium chloride; dissolving the industrial Waste iron sludge, after solid-liquid separation, the acid leaching solution reduces Fe ³⁺ under the action of a reducing agent, the reducing solution reacts with ammonium bicarbonate to form an intermediate Fe(OH) ₂ precipitation, and the intermediate is oxidized and roasted to prepare iron oxide red , the precipitation solution is crystallized under the action of an organic solvent to precipitate ammonium sulfate, and the organic solvent is evaporated to recover ammonium chloride while the precipitation solution is evaporated to recover ammonium chloride.

The process for extracting and separating iron from industrial waste iron sludge and preparing iron red is described. In the acid leaching process of waste iron sludge, part of the iron in the acid leaching solution is +3. Reduce the +3 iron in the pickling solution to +2 valence, and the reducing agent is iron powder and iron filings; prepare high value-added iron oxide red as ferrous ion solution and react with ammonium bicarbonate solution to form iron precipitation Iron red intermediate, iron red intermediate is roasted and decomposed at high temperature after oxidative drying; organic solvent crystallization, extraction and separation of ammonium sulfate process is to add organic solvent to the precipitation solution, and crystallize sulfate under the action of organic solvent to realize iron red preparation Recycling of by-products produced during the process.

A process for extracting and separating iron from industrial waste iron sludge and preparing iron red is described. In the mixed acid leaching of dilute sulfuric acid and dilute hydrochloric acid, the acid leaching solution needs to be reduced before reacting with carbonate to prepare intermediates. , the iron in the liquid phase before precipitation is +2, and the precipitate needs to be oxidized and roasted.

Said a process method for extracting and separating iron from industrial waste iron sludge and preparing iron red, said organic solvent is alcohols such as methanol and ethanol, and the organic solvent can be recycled.

The said process method for extracting and separating iron from industrial waste iron sludge and preparing iron red, in which the waste liquid is evaporated to recover solid ammonium chloride.

Advantage and effect of the present invention are:

1. The present invention is a process for extracting and separating iron from industrial waste iron sludge and preparing iron red. Compared with the prior art, the present invention has a unique processing method, high iron extraction rate, high purity iron oxide red product, simple production process, short flow process, low equipment investment, less raw material consumption, no waste liquid discharge, and easy characteristics of industrial production;

2. The present invention produces iron red and ammonium sulfate by acid leaching-organic solvent crystallization method, which has the characteristics of high economic value and wide application, and the purity of the product iron red exceeds 95%. the

3. This process is not only suitable for industrial waste iron sludge, but also for other iron-containing minerals.

4. The present invention can not only extract and separate iron from industrial waste iron sludge, but also obtain ammonium sulfate and ammonium chloride as by-products, achieving comprehensive utilization of solid waste resources.

Detailed ways

The present invention will be described in detail below in conjunction with examples.

Example 1

Main components of iron sludge in Huludao Chemical Plant (%): Fe ₂ O ₃ : 73.88; FeO: 5.98; Fe: 1.07; Others: 19.07

After drying and pulverizing the iron sludge at 70°C, take 40g and put it in the reactor, add 300mL mixed acid (c(H ⁺ )=5.45mol/L), and react in 80°C water bath for 30min. Iron oxide, ferrous oxide, iron element and a small amount of acid-soluble impurities in the iron sludge will enter the liquid phase after reacting with the acid, and other incompatible impurities still exist in the form of solid phase. Filtration allows solid-liquid separation, and the dissolution rate of iron (calculated as iron atoms) can reach more than 95%. Add 10g of iron filings to the filtrate, react at 70°C for 1 hour, reduce the ferric ions in the filtrate to ferrous ions, filter, remove the remaining iron filings and recycle. Dissolve 70g of ammonium bicarbonate in 300mL of water, add the ferrous solution dropwise into the ammonium bicarbonate solution, Fe ²⁺ first reacts with HCO ₃ ^- to form FeCO ₃ , then immediately hydrolyzes to form Fe(OH) ₂ precipitation, after filtration The solid phase was blown dry at 70°C, and Fe(OH) ₂ was oxidized to Fe(OH) ₃ , and then calcined at 600°C for 40 minutes to obtain iron oxide red with a content of more than 96%. Then add 600mL industrial ethanol to the filtrate, ammonium sulfate is precipitated in the ethanol-water phase, and dried to obtain ammonium sulfate product. The ethanol-water filtrate is distilled under normal pressure to recover ethanol, and the recovery rate can reach 97%. The remaining aqueous solution is evaporated and crystallized to obtain chlorinated ammonium products.

Example 2

Composition of iron mud in Qingdao Chemical Plant (%): Fe ₂ O ₃ : 64.32; FeO: 4.65; Fe: 1.30; few.

After drying and pulverizing iron sludge at 70°C, take 40g and put it in the reactor, add 200mL mixed acid (c(H ⁺ )=5.45mol/L), and react in 80°C water bath for 30min. Iron oxide, ferrous oxide, iron element and a small amount of acid-soluble impurities in the iron sludge will enter the liquid phase after reacting with the acid, and other incompatible impurities still exist in the form of solid phase. Then filter to make solid-liquid separation, and the dissolution rate of iron (in terms of iron atoms) can reach more than 96%. Add 8g of iron filings to the filtrate, react at 70°C for 1 hour, reduce the ferric ions in the filtrate to ferrous ions, filter, remove the remaining iron filings and recycle. Dissolve 60g of ammonium bicarbonate in 250mL of water, add the ferrous solution dropwise into the ammonium bicarbonate solution, Fe ²⁺ first reacts with HCO ₃ ^- to form FeCO ₃ , then immediately hydrolyzes to form Fe(OH) ₂ precipitation, after filtration The solid phase is blown dry at 70°C, and Fe(OH) ₂ is oxidized to Fe(OH) ₃ , and then calcined at 650°C for 40 minutes to obtain iron oxide red with a content of more than 95%. Then add 450mL industrial ethanol to the filtrate, ammonium sulfate is precipitated in the ethanol-water phase, and dried to obtain ammonium sulfate product. Ethanol and water mixed liquid are distilled under normal pressure to recover ethanol, and the recovery rate can reach 97%. The remaining aqueous solution is evaporated and crystallized to obtain chlorinated ammonium products.

Example 3

Composition of iron sludge in Qingdao Chemical Plant (%): Fe ₂ O ₃ : 86.58; FeO: 5.25; Fe: 1.98; Others: 6.19. During the acid dissolution reaction, the amount of mixed acid is larger and the reaction time is longer.

After drying and pulverizing the iron sludge at 70°C, take 40g and put it in the reactor, add 450mL mixed acid (c(H ⁺ )=5.45mol/L), and react in 80°C water bath for 50min. Iron oxide, ferrous oxide, iron element and a small amount of acid-soluble impurities in the iron sludge will enter the liquid phase after reacting with the acid, and other incompatible impurities still exist in the form of solid phase. Then filter to make solid-liquid separation, and the dissolution rate of iron (in terms of iron atoms) can reach more than 93%. Add 14g of iron filings to the filtrate, react at 70°C for 1 hour, reduce the ferric ions in the filtrate to ferrous ions, filter, remove the remaining iron filings and recycle. Dissolve 80g of ammonium bicarbonate in 340mL of water, add the ferrous solution dropwise into the ammonium bicarbonate solution, Fe ²⁺ first reacts with HCO ₃ ^- to form FeCO ₃ , then immediately hydrolyzes to form Fe(OH) ₂ precipitation, after filtration The solid phase is blown dry at 70°C, and Fe(OH) ₂ is oxidized to Fe(OH) ₃ , and then calcined at 700°C for 40 minutes to obtain iron oxide red with a content of more than 95%. Then add 800mL of industrial ethanol to the filtrate, ammonium sulfate is precipitated in the ethanol-water phase, and dried to obtain ammonium sulfate product. The ethanol-water filtrate is distilled under normal pressure to recover ethanol, and the recovery rate can reach 97%. The remaining aqueous solution is evaporated and crystallized to obtain chlorinated ammonium products.

Claims (5)

1. A process for extracting and separating iron and preparing iron red from industrial waste iron mud, is characterized in that, the method comprises the following processes: the sulfuric acid of industrial waste iron mud and hydrochloric acid mixed acid acid leaching and pickling liquid Fe ³⁺ Reduction process; reaction of ferrous sulfate solution with carbonate, oxidative roasting of precipitate intermediate to prepare iron oxide red; crystallization of precipitation liquid with organic solvent to prepare ammonium sulfate; process of evaporating and recovering organic solvent and evaporating to prepare ammonium chloride; Sulfuric acid and hydrochloric acid mixed acid dissolve industrial waste iron sludge. After solid-liquid separation, the acid leaching solution reduces Fe ³⁺ under the action of a reducing agent, and the reducing solution reacts with ammonium bicarbonate to form an intermediate Fe(OH) ₂ to precipitate. Oxidative roasting is used to prepare iron oxide red, and the precipitation solution is crystallized under the action of an organic solvent to precipitate ammonium sulfate, and the organic solvent is evaporated to recover ammonium chloride while the precipitation solution is evaporated to recover ammonium chloride. 2. a kind of process method that extracts and separates iron and prepares iron red from industrial waste iron sludge according to claim 1, it is characterized in that, the acid leaching process of described waste iron sludge, part of the iron in the pickling solution It is +3 valence, and the +3 iron in the pickling solution is reduced to +2 valence under the action of a reducing agent, and the reducing agent is iron powder and iron filings; prepare high value-added iron oxide red as a solution of ferrous ions and carbonic acid Ammonium hydrogen solution reacts to generate iron precipitate iron red intermediate, which is roasted and decomposed at high temperature after oxidative drying; the process of crystallization, extraction and separation of ammonium sulfate by organic solvent is to add organic solvent to the precipitation solution, and react with organic solvent Under the crystallization of sulfate, the recovery of by-products produced in the iron red preparation process is realized. 3. A kind of process method for extracting and separating iron and preparing iron red from industrial waste iron sludge according to claim 1, characterized in that, the mixed acid leaching of described dilute sulfuric acid and dilute hydrochloric acid is prepared by reacting with carbonate Before the intermediate, the acid leaching solution needs to be reduced, the iron in the liquid phase before precipitation is +2, and the precipitate needs to be oxidized and roasted. 4. a kind of process method of extracting and separating iron from industrial waste iron sludge according to claim 1 and preparing iron red, it is characterized in that, described organic solvent is alcohols such as methyl alcohol, ethanol, and organic solvent can be circulated use. 5. A process for extracting and separating iron from industrial waste iron sludge according to claim 1 and preparing iron red, characterized in that the solid ammonium chloride is recovered by evaporation of the waste liquid.