CN1374255A - Method of preparing high-purity iron oxide red for soft magnetic material with magnetite - Google Patents

Abstract

The present invention belongs to the field of chemical technology. The preparation process of high-purity iron oxide red for soft magnetic material with magnetite includes seven steps of sulfuric acid leaching, reduction, primary purification, secondary purification, synthesis of ammonium carbonate, filtering and drying, and incineration. In certain technological conditions, iron oxide red with 99.3% over purity is produced. The said process is simple and reliable, and has low material consumption, low power consumption, low cost, high product quality and no "three-waste" pollution.

Description

Method for preparing high-purity iron oxide red for soft magnet from magnetite

The technical field is as follows: the invention belongs to the technical field of chemical industry, and particularly relates to a method for preparing high-purity iron oxide red for soft magnetism from magnetite.

Secondly, the technical background is as follows: soft magnetic is a soft magnetic ferrite widely used in many technical fields in the power industry and the telecommunication industry, and the application of the most advanced technical field in particular promotes the rapid development of high and new technology. The iron oxide red is the main raw material for producing soft magnet, andthe present domestic iron oxide red production method is a method using the leftovers of enamel and bicycle accessories as raw materials.

Thirdly, the invention content: the invention aims to design a novel method for producing high-purity iron oxide red aiming at the defects of the existing method for producing iron oxide red, and the method has the advantages of simple process, stable raw material source, low production cost, stable consistency of product quality, no three-waste pollution and the like.

The technical scheme is as follows: the method for preparing the high-purity iron oxide red for the soft magnet by using the magnetite is characterized in that the process method comprises seven working procedures of sulfuric acid leaching, iron sheet reduction, primary purification, secondary purification, carbon-ammonia synthesis, filtering and drying and calcination to obtain a product; the process conditions are as follows: in the sulfuric acid leaching process, the addition of sulfuric acid is 0.8-1.5 times of the theoretical value of Fe, Ca, Mg and Al in the ore when the four metal elements are completely dissolved in the sulfuric acid solution, the leaching time of the leaching process is 0.5-6 hours, and the leaching temperature of the leaching process is 50-114 ℃; the adding amount of iron sheets in the iron sheet reduction procedure is 0.8-1.8 times of the theoretical value, and the reduction reaction temperature is 30-95 ℃; using NH in a primary cleaning process₃·H₂Adjusting the pH value of the solution to 3.5-8.0 by using O water; NH in the secondary purification process₃·H₂Adjusting the pH value of the solution to 1.0-6.0 by using O water, and controlling the temperature of primary purification and secondary purification to 50-98 ℃; the reaction temperature of the carbon-ammonia synthesis process is 35-95 ℃, the feeding speed is 100-450 ml/h, and the stirring speed is 50-650 r/min; the calcination temperature in the calcination process is 250-1200 ℃, and the calcination time is 18-150 minutes. The sulfuric acid leaching process is to react magnetite powder with sulfuric acid water solution to produce FeSO under certain conditions₄And Fe₂(SO₄)₃And meanwhile, impurity ions such as Ca, Mg, Al and the like are also transferred into the solution. The addition amount of sulfuric acid, the leaching time and the leaching temperature in the sulfuric acid leaching process are important process conditions, the optimal process conditions are that the addition amount of the sulfuric acid is 1.0-1.20 times of the theoretical value of Fe, Ca, Mg and Al in the ore which are all dissolved in the sulfuric acid solution, and the leaching temperature is 70-104 ℃. The theoretical value of the added amount of the sulfuric acid is determined by testing the contents of Fe, Ca, Mg and Al in the ore through tests, and then obtaining the added amount of the sulfuric acid as the theoretical value through a theoretical calculation method, and the tests and the calculations are carried outFor the prior art, it is not described here in more detail. Filtering to remove residue after leaching, and reserving leaching solution for use. The iron sheet reduction procedure is to use the simple substance of iron sheet to reduce a large amount of Fe in the leached solution³⁺And (3) carrying out a reduction reaction. The iron sheet adding amount and the reduction reaction temperature in the iron sheet reduction procedure are important process conditions, and the optimal process conditions areThe adding amount of the iron sheet is 1.0-1.6 times of the theoretical value, and the reduction reaction temperature is 40-80 ℃. The influence of the addition amount of the iron sheet on the speed of the reduction reaction is large, and the residual iron sheet after the reaction can be reused. The theoretical value of the addition of the iron sheet is determined by actually measuring Fe in the leaching solution³⁺The average content is calculated by a chemical reaction formula, and the reaction formula is . The primary purification process aims at removing Al and Si in the ferrous sulfate solution, and NH is selected so as not to introduce other metal ions₃Adjusting pH of the solution to 5.0-5.9 with water as neutralizer, adding appropriate flocculant, and filtering to remove Al and SiO₂. The secondary purification is intended to remove suspended matter from the primary purification solution by adding a certain amount of an additive such as NH₃·H₂O water, adjusting the pH value of the solution to 2.0-3.5, adding proper amount of flocculant, such as aluminum sulfate, aluminum hydroxide, high polymeric aluminum-iron flocculant, etc., and filtering to obtain purified liquid. The carbon-ammonia synthesis process is FeSO after secondary purification and filtration₄Adding NH into the solution₄HCO₃To obtain FeCO₃Precipitation and (NH)₄)₂SO₄The synthesis reaction is carried out in a reactor having an elevated tank. The optimal reaction temperature in the carbon-ammonia synthesis process is 50-80 ℃, the optimal feeding speed is 180-300 ml/h, and the optimal stirring speed is 100-500 r/m. The filtering and drying process is to mix FeCO₃Separating the precipitate, washing, discharging the solution and washing liquid, and adding FeCO₃The solid is dried to remove water to facilitate subsequent calcination. The calcining procedure is to mix FeCO₃Decomposed and oxidized into Fe at high temperature₂O₃The optimum temperature for calcination is 650-950 ℃. Cooling and inspecting to obtain qualified product, and the product Fe produced by said process₂O₃The content of (A) is more than 99.2%.

The method has the advantages of simple process, wide and unlimited raw material source, large-scale production, low material consumption, low energy consumption, low production cost, high product quality, stable consistency, good economic benefit, no three-waste pollution and the like.

Fourthly, the specific implementation mode:

1. the laboratory implementation: the raw ore is collected from No. four ore bodies of iron ore of temple in Qinghai Dulan county, the raw ore is subjected to magnetic separation, the content of ferroferric oxide is 93.4 percent, and iron sheets are made of ordinary low-carbon steel; NH (NH)₄HCO₃The content of N in the ammonia water is 17 percent, the ammonia water is industrial grade and contains 20 percent of ammonia; the fresh water is tap water, and the purifying flocculant is an aluminum hydroxide solution; the concentration of the aqueous sulfuric acid solution was 25%. The addition of sulfuric acid in the sulfuric acid leaching process is 1.05 times of the theoretical value, the leaching temperature is 95 ℃, the leaching time is 4 hours, and the leaching rate reaches 96%. The addition amount of iron sheets in the reduction process of the iron sheets is 1.4 times of the theoretical value, the reduction reaction temperature is 70 ℃, the pH value of the solution is adjusted to 4.8-S.2 by ammonia water in the primary purification process, the pH value of the solution is adjusted to 2.0-2.5 by ammonia water in the secondary purification process, and the solution is purified for the first timeThe temperature for melting and secondary purification is 70 +/-5 ℃. The reaction temperature of the carbon-ammonia synthesis is 60 +/-5 ℃, the stirring speed is 200 revolutions per minute, and the feeding speed is 200ml per hour. The calcining temperature is 750 +/-50 ℃, and the product is obtained after the calcining time is 50 minutes and then the product is cooled.

2. The intermediate test is expanded, and crude ore, namely Fe, is collected from four ore bodies of iron ore of temple in Qinghai Dulan county₃O₄Content of 62.8 percent, magnetic separation Fe after grinding₃O₄The content is 93.4 percent, and 2 tons of concentrate is obtained. 98% of sulfuric acid, 20% of ammonia water and 17% of ammonium bicarbonate. Adding a certain amount of bottom water into a reaction kettle of 1m3, adding magnetite powder under stirring, adding concentrated sulfuric acid, heating to 105 ℃, keeping the temperature for 4 hours, and finishing acid leaching. Diluting to a certain volume of about 800L with tap water, stopping stirring, slowly adding iron sheet 1.2 times of theoretical value, reducing at 80 deg.C to obtain FeSO with final pH of 2.5-4.0₄And (3) solution. Adjusting pH of the solution to 5.4 with ammonia water for primary purification, adding flocculant, heating to 95 deg.C, filtering, removing residue, adjusting pH to 3.0 with ammonia water for secondary purification, adding flocculant, stirring for 10 min, and filtering to remove residue. The secondary purification liquid is heated to 70 ℃, the stirring speed is 180 r/min, and the carbon ammonia feeding speed is 250 ml/h. Filtering and drying to obtain black FeCO₃And calcining the semi-finished product in a 900 ℃ calcining kiln for 40 minutes, taking out and cooling to obtain the product.

Claims (5)

1. A method for preparing high-purity iron oxide red for soft magnetism by using magnetite is characterized by comprising the following steps: the process method comprises seven procedures of sulfuric acid leaching, iron sheet reduction, primary purification, secondary purification, carbon-ammonia synthesis, filtering and drying and calcining to obtain a product; the process conditions are as follows: in the sulfuric acid leaching procedure, the addition of sulfuric acid is 0.8-1.5 times of the theoretical value of Fe, CaMg and Al metal elements in the ore which are completely dissolved in a sulfuric acid solution, the leaching time of the leaching procedure is 0.5-6 hours, and the leaching temperature of the leaching procedure is 50-114 ℃; the adding amount of iron sheets in the iron sheet reduction procedure is 0.8-1.8 times of the theoretical value, and the reduction reaction temperature is 30-95 ℃; using NH in a primary cleaning process₃·H₂Adjusting pH of O water solution to 3.5-8.0, and purifying NH in the second time₃·H₂Adjusting the pH value of the solution to 1.0-6.0 by using O water, and controlling the temperature of primary purification and secondary purification to 50-98 ℃; the reaction temperature of the carbon-ammonia synthesis process is 35-95 ℃, the feeding speed is 100-450 ml/h, and the stirring speed is 50-650 r/min; the calcination temperature in the calcination process is 250-1200 ℃, and the calcination time is 18-150 minutes.

2. The method as claimed in claim 1, wherein the amount of sulfuric acid added in the sulfuric acid leaching process is 1.0-1.10 times of the theoretical value of Fe, Ca, Mg and Al dissolved in the sulfuric acid solution, and the leaching temperature is 70-104 ℃.

3. The method as set forth in claim 1, wherein the amount of the iron pieces added in the iron piece reduction step is 1.0 to 1.6 times of the theoretical value, and the reduction reaction temperature is 40 to 80 ℃.

4. The method as set forth in claim 1, wherein the reaction temperature in the carbon-ammonia synthesis step is 50-80 ℃, the feeding rate is 180-300 ml/h, and the stirring rate is 100-500 rpm.

5. The method as set forth in claim 1, wherein the calcination temperature in the calcination step is 650-950 ℃.