RU2623928C2 - Method of deep recycling iron-containing wastes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method comprises precipitating from the said solutions of solid ferrous sulfate of ferrous divalent Fe₂SO₄⋅7H₂O. Then it is sent to biooxidation solution, consisting of cultivated on a nutrient medium 9K microorganisms Ac. ferrooxidans and Ac. Thiooxidans, in a continuous vapour regime with a flow at atmospheric pressure for 12-50 hours at an average oxidation rate of 1-1.5 g/l per hour with transfer of ferrous iron to trivalent. Further, alkali is added to increase the pH of the solution and to obtain a precipitate of solid ferrous sulfate and to perform its ultrasonic work-up to obtain a product for the production of iron oxide pigments.

EFFECT: increasing the depth of processing of iron-containing waste, reducing waste disposal costs and obtaining highly liquid transparent nanoscale pigments.

5 cl, 1 ex

Description

The invention relates to the disposal of mining and metallurgical iron-containing waste, and in particular to a deep biohydrometallurgical processing of iron-containing waste to produce mineral iron oxide pigments. The method can be used in the mining and processing and metallurgical industries for the processing of natural and industrial mineral raw materials.

Current trends in the mining iron ore industry are characterized by a continuous increase in the degree of enrichment of raw materials of constantly deteriorating quality, as well as more stringent requirements for iron ore products in light of the increased use of cokeless methods of steel production, requiring the use of high-quality concentrates with a minimum content of impurities, and the requirements to reduce the environmental load on environment. In the iron ore industry, as well as in non-ferrous metallurgy, the category of “hard-to-concentrate” ores, that is, low-quality, finely disseminated ores with a complex material composition, has appeared. The processing of such raw materials is accompanied by the formation of large volumes of solid (dust, slag, scale, cinder, metal shavings, washing and hydrocyclone slurries, etc.) and liquid (acidic wastewater from processing and metallurgical industries, drainage water, etc.) waste with a high iron content . The relevance of involving these wastes in the processing is confirmed not only by the prospect of solving environmental problems, but also by the possibility of increasing the efficiency of using natural mineral raw materials to produce highly liquid marketable products, in particular high-quality iron oxide mineral pigments, which will solve the issue of import substitution and develop the domestic pigment market.

A known method of processing ash and slag waste, including magnetic separation to separate the iron-containing concentrate from ash, screening with the release of quicklime, ash gravel and sand, followed by the separation of heavy metals from sand by gravity and separation of sand and coal by electrical conductivity (RU No. 2206626, IPC С22В 7 / 02 2003).

The disadvantage of this method of processing ash and slag waste is the low degree of extraction of valuable components and high losses of associated metals, including rare ones.

A known method for producing iron-containing pigment, according to which a solution obtained by bio-leaching of metallurgical waste and containing iron in trivalent form, is treated with an aqueous solution of potassium carbonate or sodium or ammonium and magnesium chloride or sulfate to form magnesium carbonate (or partially hydrogen carbonate), which is upheld, decanted, washed several times, add a salt solution of Fe (III), which allows to increase the filtration rate of the pulp (Patent RU 2400505, C09C 1/24, publ. 09/27/2010).

The disadvantage of this method is the need for additional supply of ferric salt before the operation to obtain iron-containing pigment, as well as the focus of the technology only on increasing the speed of filtration of the pulp.

A well-known complex method of processing slag, including magnetic separation and gravitational enrichment to obtain concentrate and tailings with the direction of the latter for cavitation treatment and bioleaching with continuous aeration to retrieve valuable components from the slag matrix, (Pat. RU 2350666, IPC С22В 7/04, С22В 3 / 18, published March 27, 2009).

The disadvantages of the processing method include the implementation of bioleaching in static mode with a periodic change of solution, which determines the labor-intensive loading and unloading into tanks of large masses of the initial tailings, high energy consumption for cavitation treatment and removal of potentially suitable residual solutions to the dump without disposal.

The closest in technical solution and the achieved result is a method of processing technogenic iron-containing sludge with valuable components, including washing the sludge, their acoustic treatment, irrigation with a bacterial solution with an intensifying catalyst with constant aeration and periodic loosening, removing valuable components from the liquor and directing the remaining liquor to receive iron oxide biopigment (Patent RU 2387721, C22 7/00, C22 5/00, publ. 04/27/2010).

The disadvantage of this method is the use in the catalyst circuit for the intensification of bioleaching, as well as loosening operations, which significantly increases the cost of implementing the technology.

The purpose of the present invention is to increase the efficiency of the use of mineral raw materials by deep processing of industrial waste with obtaining additional liquid products, reducing waste disposal costs, minimizing the negative impact of stored waste and reducing the environmental load on the environment.

The technical result consists in increasing the efficiency of the use of mineral raw materials by increasing the depth of processing iron-containing waste using biotechnology, reducing the cost of waste disposal and obtaining highly liquid transparent pigments of nanoscale size.

The essence of the method, achieving the purpose of the invention, is as follows. Solid iron-sulfate wastes obtained by precipitation from ferric acid solutions of mining and metallurgical industries (ferrous iron, Fe ₂ SO ₄ ⋅ 7Н ₂ О) are biooxidized by treatment with a solution with an active bacterial complex consisting of Ac microorganisms cultured on a nutrient medium 9K. ferrooxidans and Ac. Thiooxidans. Initial indicators of a solution with an active bacterial complex for bacterial oxidation: the concentration of microorganism cells - 10 ⁶ -10 ⁷ in 1 ml, pH - 1.8-2.0, Eh - 640-680 mV, temperature - 23-32 ° C. A description of the methods of isolation, accumulation (cultivation), quantification and determination of the activity of microorganisms used in bacterial oxidation and leaching of mineral raw materials is described in the relevant literature (for example: Biotechnology of metals. Practical guide. Scientific editor: G.I. Karavayko ( USSR) and other Moscow: Center for the International Project of the State Committee for Science and Technology in accordance with the program of the international project of the USSR / UNEP “Biotechnology of metals as an economically acceptable method of rational use of mine ial resources ", 1989).

The process is carried out in a continuous tank mode with a duct at atmospheric pressure, as a result of which ferrous iron is oxidized to ferric to obtain a solution with ferric iron concentration of 15-60 g / l for 12 to 50 hours at an average oxidation rate of 1-1.5 g / l per hour, depending on the initial concentration of ferrous iron. Then, using alkali (sodium hydroxide, potassium hydroxide), the pH of the resulting ferric iron solution is increased to 2.8-3.5, as a result of which solid ferric sulfate is formed and precipitated from the liquid phase. The specific alkali consumption for producing 1 kg of iron-containing sludge is 300-350 g; excess alkali consumption relative to 350 g leads to undesirable gelation in the liquid phase. The obtained iron-containing precipitate, consisting of particles of regular spherical shape with a size of 500-600 nanometers, is subjected to ultrasonic treatment for 20-100 seconds, reducing the particle size to 20-50 nanometers and, accordingly, increasing the specific surface area. The iron-containing precipitate meets the standards for products for producing high-quality transparent mineral iron oxide pigments in terms of parameters: spherical shape of particles, nanoscale particle size, high specific surface area, hiding power, color rendering, oil absorption.

The advantages of the method:

- the possibility of deep processing of mining and metallurgical waste with the receipt of environmentally friendly biotechnology liquid marketable products that meet the requirements of the consumer market;

- the relevance and the possibility of obtaining transparent mineral pigments with high technological properties comparable with the properties of high-quality mineral and synthetic pigments: the correct spherical morphology of nanoscale particles, high specific surface area, hiding power, color rendering, oil absorption;

- reduction of the technogenic load on the environment due to the involvement of metallurgy waste (accumulated and current production) in the processing with the maximum reduction of their negative impact on the environment;

- lack of need for large production facilities;

- reduction of technological and energy costs;

- meets the principles of resource conservation and environmental safety.

Example

Solid ferrous sulfate precipitates (Fe ₂ SO ₄ ⋅ 7Н ₂ О) obtained by precipitation from sulfuric acid iron-containing solutions of gas treatment sludge from an electric arc furnace when processing waste from rolled alloys were sent to biooxidation in a continuous tank mode with a duct using a solution with an active bacterial complex of microorganisms Ac. ferrooxidans and Ac. Thiooxidans. The complex was pre-cultured on 9K growth medium until the concentration of microorganism cells reached 10 ⁶ -10 ⁷ in 1 ml of solution. Initial indicators of the bacterial solution: pH - 1.95, Eh - 658 mV, temperature - 25 ° C, pressure - atmospheric. Ferrous iron was oxidized to ferric to obtain a solution with a ferric iron concentration of 32 g / l for 20 hours. Then, by feeding a solution of sodium hydroxide, the pH of the resulting ferric iron solution was increased to 3.2 to obtain a solid precipitate of ferric iron sulfate. The specific alkali consumption for producing 1 kg of iron-containing precipitate was 340 g. The obtained precipitate, consisting of particles of regular spherical shape with a size of 550 nanometers with a specific surface area of 1.98 m ² / g, was sent for ultrasonic treatment for 45 seconds, resulting in a coarseness particles decreased to 55.1 nm with a corresponding increase in the specific surface area to 52.7 m ² / g An increase in the duration of ultrasonic treatment to 80 seconds made it possible to reduce the dimension of solid particles to 25 nm. The dried iron-containing precipitate meets the standards for products to obtain high-quality transparent mineral iron oxide pigments of various colors.

Claims (5)

1. A method for the disposal of waste sulfuric acid iron-containing solutions of hydrometallurgical industries, including the production of ferrous Fe ₂ SO ₄ ⋅ 7H ₂ O by precipitation from the above solutions of solid iron sulfate, directing it to biooxidation with a solution with an active bacterial complex consisting of Ac microorganisms cultured on nutrient medium 9K. ferrooxidans and Ac. Thiooxidans, in a continuous tank with a channel at atmospheric pressure for 12-50 hours at an average oxidation rate of 1-1.5 g / l per hour with the conversion of ferrous iron to ferric, adding alkali to the resulting solution to increase the pH of the solution and obtain a precipitate solid ferric sulfate and its ultrasonic testing to produce a product for the production of high-quality transparent mineral iron oxide pigments. 2. The method according to p. 1, characterized in that the biooxidation is carried out with a solution with an active bacterial complex with initial values of the concentration of microorganism cells 10 ⁶ -10 ⁷ in 1 ml, pH 1.8-2.0, Eh 640-680 mV, temperature 23-32 ° C. 3. The method according to p. 1, characterized in that the pH of the ferric iron solution is increased with alkali to 2.8-3.5 to obtain a precipitate of solid ferric sulfate with spherical particles of 500-600 nanometers in size. 4. The method according to p. 1, characterized in that as the alkali for the deposition of ferric sulfate, sodium hydroxide or potassium hydroxide is used at a specific flow rate of 300-350 g per 1 kg of sediment. 5. The method according to p. 1, characterized in that the obtained iron-containing precipitate is subjected to ultrasonic treatment for 20-100 seconds with a decrease in particle size to 20-50 nanometers and an increase in specific surface area.