RU2413012C1 - Procedure for purification of iron containing material from arsenic and phosphorus - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: procedure consists in crumbling material and in its leaching. Also, material crumbling and leaching is performed in concentrated solution of sodium chloride when compounds of arsenic and phosphorus are dissolved to suspension. Produced suspension is subjected to gravitation separation to a solid phase of concentrated iron containing material and to suspension of dispersed impurities. The separated solid phase of iron containing material is further subjected to washing with acid concentrated solution of sodium chloride.

EFFECT: raised contents of iron in iron containing material at diminished contents of arsenic and phosphorus to standard values, reduced duration of process, and consumption of reagents and lowered prime cost.

5 cl, 1 dwg, 1 tbl, 3 ex

Description

The invention relates to the field of mining and metallurgical and metallurgical industries, and in particular to physicochemical methods for preparing iron, iron-manganese, iron-titanium, iron-chromium, manganese and other ores, concentrates, sponge iron, metallized pellets, crits, and can be used for increasing the iron content in the iron-containing material and removing unwanted impurities from it, especially vanadium.

Iron-containing materials for use in industry, for example, in blast-furnace smelting, steelmaking, are enriched to obtain concentrates containing up to 71% iron, up to 0.15% arsenic and up to 0.25% phosphorus [Blast furnace production. Handbook, Volume 1, Preparation of ores and a blast furnace process, edited by Wegman E.F. M .: Metallurgy, 1989, p. 496; Arsentiev P.P. and other General metallurgy, M .: Metallurgy, 1986, S. 360].

Among the various iron-containing materials to be processed and refined, the most interesting are iron ores with a relatively high iron content (up to 35%), the specific gravity of which is continuously increasing due to depletion of rich ore reserves, and currently exceeds 20%. As a rule, these are sedimentary ores of marine peloid origin, which have a significant advantage - the low cost of their extraction. Such ores in Ukraine include ores of the Kerch deposit containing 37-39% iron, 15-35% silicates, up to 1% phosphorus, up to 0.2% arsenic and up to 0.1% vanadium, as well as up to 4% manganese, etc. alloying elements; ores of the Kremenchug deposit containing from 34 to 58% iron, 13-43% silicates, impurities of phosphorus, arsenic and sulfur; ores of the Sea of Azov. In the Russian Federation, such ores include ores of the Tula, Lisakovsky, Angaro-Ilim and other deposits. In Kazakhstan, many deposits of iron ore of sedimentary metamorphosed origin also have elevated amounts of phosphorus and arsenic. Similar deposits exist in other countries (Australia, China, India, Canada). Therefore, the processing of such ores is a difficult but urgent problem, but it justifies itself due to the presence of alloying elements in the ores and the relative simplicity of their extraction, usually by open methods.

In this case, chemical technologies are used for processing such complex iron-containing materials not only in non-ferrous, but also in ferrous metallurgy.

There is a method of processing iron-containing materials, in which the calcined ore is treated with a dilute acid solution at high ratios of solid and liquid (T: G) phases and a significant process time (up to 25 hours), with subsequent ion-exchange extraction of undesirable impurities [French Patent No. 1505100, cl . C22B 3/06, publ. 1963].

The disadvantages of this method are the low percentage of extraction of impurities, the duration of leaching and a significant amount of the liquid phase, which reduces productivity and increases cost.

There is also a method of cleaning ore from impurities by oxidative calcination at a temperature of 800-1000 ° C for 1 hour, leaching with 49% acid, at T: W = 1: 1-1.2 and a temperature of 20-50 ° C for 2 -3 hours [RF Patent No. 2184158, cl. C22B 1/11, publ. 06/27/2002].

The disadvantages of the method are, along with the relatively high losses (up to 4-8%) of iron and acid, the chemical aggressiveness of the solutions and the low recovery of arsenic due to the formation of iron arsenates which are hardly soluble in 49% acid.

A known method of leaching from ore calcined at a temperature of 500-600 ° C for 1-1.5 hours, arsenic and phosphorus diluted with sulfuric acid at elevated (60-80 ° C) temperatures, T: W = 1: 3-1: 5 and the duration of the process 2-3 hours [Dukino R.D., England V.M. Phosphorus in Iron Ores of the Hemersleys Range, Australian Institute of Mining (Austral, IMM) 1977, No. 5, pp. 179-202].

The disadvantages of the method are the low extraction of arsenic and phosphorus and the significant costs of the leach solution.

There is also a method of extracting unwanted impurities from iron ore by treating it in the presence of 6-7% soda at a temperature of 300 ° C, followed by leaching of impurities with hot water [US Patent No. 2928024, cl. C22B 1/11, publ. 1975].

The disadvantages of the method include the low extraction of arsenic and phosphorus at a high flow rate of the leaching solution.

A known method of processing iron-containing material with a 40-50% alkali solution in autoclaves at a temperature of 125-140 ° C [8th International Congress on Mineral Processing, vol. 2, Leningrad, 1969].

However, this method requires complex hardware design, high concentrations of aggressive alkali, as well as large volumes of water for washing it off, which complicates the regeneration of solutions and makes the process economically disadvantageous.

The closest in technical essence to the claimed method is a method of purification of iron-containing material from arsenic and phosphorus, including grinding the iron-containing material in a mill, followed by leaching of arsenic and phosphorus with a 2% alkali solution at T: W = 1: 10 and the duration of the process up to 48 hours [Syrtlanova T.S. and other Izvestiya SB AS USSR, ser. Chem. Science, 1979, issue 3, No. 7, pp. 50-55].

However, this method is suitable only for sulfide ores, while in the leached material remains from 0.22% to 1.5% of arsenic. At the same time, its content, for example in iron ores, does not exceed 0.1-0.2%, at high temperatures and T: W the alkali consumption of the ore mass is up to 20%, the process has a longer duration, and the iron content in iron-containing material after treatment with alkali does not increase.

The basis of the invention is the task of improving the method of purification of iron-containing material from arsenic and phosphorus, in which the grinding and leaching of the material in an alkaline concentrated solution of sodium chloride, with the dissolution of compounds of arsenic and phosphorus, to obtain a suspension, which is subjected to gravitational separation into a solid phase of the enriched iron-containing material and a suspension of dispersed impurities, washing the separated solid phase of the iron-containing material with acid concentrate bath solution of sodium chloride, provide an increase in the iron content in the iron-containing material while reducing the content of arsenic and phosphorus in it to standard values, this reduces the duration of the process, reduces the content of arsenic and phosphorus in the iron-containing residue, reduces the consumption of alkaline reagent, reduces its losses, reduces cost. .

The problem is solved in that in the method of purification of iron-containing material from arsenic and phosphorus, including grinding the material and its leaching, according to the invention, the following differences are provided:

- grinding and leaching of the material is carried out in an alkaline concentrated solution of sodium chloride, with the dissolution of compounds of arsenic and phosphorus, to obtain a suspension;

- the resulting suspension is subjected to gravitational separation into the solid phase of the enriched iron-containing material and a suspension of dispersed impurities;

- the separated solid phase of the iron-containing material is washed with an acidic concentrated sodium chloride solution.

In addition, grinding and leaching of iron-containing material is carried out in an alkaline concentrated solution of sodium chloride with pH = 11-12 at T: W = 1: 1.25; the concentration of sodium chloride in the solution is maintained at a level of 15-28 wt.%; the separated solid phase of the enriched iron-containing material, before washing with an acidic concentrated sodium chloride solution, is washed with a concentrated aqueous solution of sodium chloride, which is taken in an amount equal to the moisture content of the solid phase material; washing the solid phase of the enriched iron-containing material is carried out with an acidic concentrated solution of sodium chloride with pH = 1-2 batch T: W = 1: 1.25.

The invention is illustrated by the technological scheme of purification of iron-containing material with its enrichment, shown in the drawing.

The method is as follows.

The mill is loaded with iron-containing material, water, sodium chloride and sodium hydroxide, which is introduced in an amount sufficient to maintain a pH in the range of 11-12. Grinding and leaching of iron-containing material is carried out to obtain particles of enriched iron-containing material (hematite, wustite, metallic iron) fractions of 0.063-0.25 mm and particles of impurities (silicates, carbonates, highly dispersed carbon and iron oxides) fractions minus 0.063 mm. Under such conditions, as was established by the inventors, leaching from iron-containing material and subsequent dissolution of arsenic and phosphorus compounds in an alkaline concentrated NaCl solution occur. Other alkali-soluble compounds, for example, vanadium, zinc, dissolve simultaneously.

The suspension obtained after grinding is subjected to gravitational separation (deposit). At the same time, dense particles of hematite, wustite and metallic iron are concentrated in a coarse dispersed sediment, which allows increasing the iron content, in terms of metal, from 35 to 45% wt. In the starting material, up to 65-95% wt. - in enriched iron-containing material. At the same time, the content of arsenic and phosphorus decreases, respectively, from 0.2-0.3 to 0.05-0.1% As and from 0.5-1% to 0.2-0.25 wt.% P, and also are removed other alkali soluble impurities. This result is a consequence of the fact that, as it was established by the inventors, with the participation of a concentrated solution of sodium chloride, in the presence of minor alkali additives (0.1-5% by weight of sodium chloride), stable highly dispersed suspensions (colloidal solutions) of iron ore impurities are formed, having a low density - silicates, carbonates, carbon, hydrated iron oxides, phosphates and arsenates. At the same time, materials rich in iron (hematite, wustite, sponge iron, kritz) are contained in a suspension of coarse particles and are easily amenable to gravitational enrichment - depositing.

The enriched precipitate of iron-containing material is separated from the residual liquid phase, for example by filtration, and washed with a concentrated solution of sodium chloride in an amount equal to the moisture content in the solid phase of the iron-containing material. Under these conditions, a concentrated solution of sodium chloride almost completely replaces a slightly alkaline concentrated solution of sodium chloride in a precipitate of iron-containing material. As was established by the inventors, under such conditions, there is no decrease in the solubility of the phosphates and arsenates contained in the solution, and they are removed from the precipitate. In the case of using pure water for washing iron-containing material, the solubility of phosphates and arsenates is reduced by 5-10 times, and the resulting highly dispersed nanoparticles of phosphates and arsenates are sorbed on the surface of the iron-containing material, polluting it.

The iron-containing material is washed with a weakly acid concentrated solution of sodium chloride with a pH of 1-2 at T: W = 1: 1-1.25. As it was established by the inventors, under these conditions, phosphates partially sorbed by the surface of the iron-containing material, as well as minor impurities of arsenates and vanadates, dissolve in a slightly acidic solution and are removed by filtration. This technique further increases the degree of purification of the iron-containing material from compounds of phosphorus, arsenic and vanadium, and the dissolution of iron itself under such conditions practically does not occur.

The concentration of sodium chloride in its concentrated solutions is maintained within the range of 15-28 wt.% NaCl. As it was established by the inventors, in a slightly alkaline solution at pH = 11-12, a high concentration of sodium ions provides the same conditions for leaching of phosphates and arsenates from iron-containing material, as well as a NaOH solution with a concentration of 15-28 wt.%.

The following are examples of the method using the sedimentary ore of the Kyz-Aul deposit of the Kerch iron ore basin as the starting material, the ore had the following chemical composition (wt.%): SiO ₂ = 7.1; Al ₂ O ₃ = 4.1; CaO = 4.5; Mn = 12.3; Fe = 39.1; As = 0.33; P = 0.58; V = 0.05.

Before purification from arsenic and phosphorus, the ore was subjected to heat treatment by the direct reduction of iron [Arsent'ev PP, Yakovlev VV, Krasheninnikov MG and others, General metallurgy, Moscow, Metallurgy, 1986, p. 360].

Example 1

1160 g of metallized pellets of iron ore were divided into fractions:

fraction 1 (-0.25 mm) weighing 221 g, containing (wt.%): (Fe + Mn) = 94.8; CaO · SiO ₂ = 4.2; V = 0.15; Y = 0.17; As = 0.15;

fraction 2 (-0.25 + 0.08 mm) weighing 519 g, containing (wt.%): (Fe + Mn) = 61.4; CaO · SiO ₂ = 3.7; SiO ₂ = 8.1; Al ₂ O ₃ = 5.4; V = 0.05; Y = 0.07; Ni = 0.11; As = 0.22; Zr-0.05;

fraction 3 (-0.08 mm) weighing 420 g, which is a waste and containing (wt.%): (Fe + Mn) = 12.7; As = 0.35, the rest are silicates and coke.

Fraction 2, weighing 519 g, was placed in a steel ball mill, where 248 g of sodium chloride, 770 g of water and 3 g of sodium hydroxide were added until a solution with pH = 12 was obtained (T: W = 1: 1, NaCl concentration = 24.36 wt.%). The grinding process was carried out for 2 hours, the suspension was separated from the balls and filtered to a moisture content of 30.4 wt.%. The filter residue was washed with 158 g of a NaCl solution with a concentration of 24.36 wt.% (The amount of solution is equal to the moisture content in the solid residue on the filter). The filter residue was washed with 519 g of a NaCl solution with a concentration of 24.36 wt.% And a H ₂ SO ₄ concentration of 0.5% in it, providing a solution with pH = 1, the filtrates were mixed and used to isolate solid arsenic compounds from them, phosphorus and vanadium. The filter residue was washed with 519 g of water and dried, obtained after elutriation of 421 g of iron ore concentrate containing (wt.%)

(Fe + Mn) = 69.8; As = 0.07; P = 0.13.

Example 2

1000 g of iron-containing pellets were placed in a steel ball mill. A solution of 250 g of NaCl in 1000 g of water was prepared. 5 g of NaOH was added to the resulting 20% NaCl solution to pH = 12. An alkaline solution of sodium chloride was added to the mill to iron-containing pellets (T: W = 1: 1.25), ground for 2 hours. The resulting suspension was separated from the solution, the residue with a moisture content of 29.1 wt.% Was washed with 219 g of a 20% NaCl solution, then 1000 g of water. The solid residue was separated from the suspended particles and dried. Received 621 g of iron concentrate with a content (wt.%):

(Fe + Mn) = 67.1; Y = 0, l; V = 0.1; Ni = 0.1; As = 0.08; P = 0.16.

Example 3

An iron ore powder in an amount of 1000 g was mixed with coke powder (coke), kept under reducing conditions at a temperature of 1300 ° C until the iron was completely reduced. The obtained cake in an amount of 1105 g was subjected to dry grinding and sieving on a sieve No. 0063 and No. 05. got:

- 606 g of iron-containing material in the form of granules -3 + 0.5 mm and dust containing (wt.%): (Fe + Mn) = 89.8; As = 0.23; P = 0.48;

- 591 g s (wt.%): (Fe + Mn) = 12.7%;

- 8 g - irretrievable loss during separation.

606 g of iron-containing material in the form of granules and dust was placed in a ball mill, to which 606 g of water, 180 g of NaCl and 3 g of NaOH were added, crushed for 2 hours. A suspension of solid particles of a fraction minus 0.25 mm was obtained, which was filtered. A solid residue with a moisture content of 29.5% was washed with 179 g of a 20% NaCl solution with pH = 7, and then 606 g of a 20% NaCl solution with pH = 1.5. The precipitate was washed with 606 g of water and mixed with 1200 g of water, and subjected to gravitational separation. A fraction of 0.063 mm in an amount of 25 g was removed with a suspension, and the heavy precipitate was separated from water and dried. Received an iron powder fraction of -0.25 + 0.063 mm in the amount of 577 g with a content, wt.%:

(Fe + Mn) = 94.1; As = 0.06; P = 0.06; S = 0.01; CaO = 1.1; SiO ₂ = 0.9; Al ₂ O ₃ = 0.7; C = 3.2.

Other examples of the method of purification of iron-containing material from arsenic and phosphorus are given in the table. There is an example (No. 0) of the method according to the prototype.

Table Example No. The concentration of NaCl,% The concentration of NaOH,% T: F The duration of the process, h The content in the solid residue, wt.% Fe + Mn As P 0 0 2 1:10 48 39.3 0.31 0.55 one 24.36 0.39 1: 1 2 69.8 0,07 0.13 2 20,0 0.5 1: 1.25 2 67.1 0.08 0.16 3 28.0 0.5 1: 1.25 2 68.3 0,07 0.12 four 15.0 0.5 1: 1.25 2 65,4 0.13 0.18 5 12.0 0.5 1: 1.25 2 54.3 0.19 0.28

From the analysis of the results given in the table, the following conclusions can be drawn.

1. The addition of sodium chloride to the leach solution can reduce the process time by an order of magnitude, while reducing the content of arsenic and phosphorus in the iron-containing residue by 70-85%.

2. The method allows the simultaneous removal of arsenic and phosphorus to enrich the iron-containing material in the metal (Fe + Mn) from 51.3 to 65.4-94.1%.

3. The low initial concentration of alkali (0.4-0.5%) allows, including due to the return to production of purified filtrates, to reduce the consumption of alkaline reagent and reduce its loss by 20-25 times.

Using the proposed method will enrich iron ores with a low iron content, reduce the content of arsenic and phosphorus in them, reduce the duration and increase the productivity of the process, reduce the cost of an alkaline reagent and reduce the cost of the process.

Claims (5)

1. The method of purification of iron-containing material from arsenic and phosphorus, including grinding the material and leaching, characterized in that the grinding and leaching of the material is carried out in an alkaline concentrated solution of sodium chloride with the dissolution of compounds of arsenic and phosphorus to obtain a suspension, which is subjected to gravitational separation into a solid phase enriched iron-containing material and a suspension of dispersed impurities, the separated solid phase of the iron-containing material is washed with acid concentrate Sodium chloride solution. 2. The method of claim 1, characterized in that the grinding and leaching of the iron-containing material is carried out in an alkaline concentrated solution of sodium chloride with a pH of 11-12, at T: W = 1: 1.25. 3. The method according to claim 1, characterized in that the concentration of sodium chloride in the solution is maintained at a level of 15-28 wt.%. 4. The cleaning method according to claim 1, characterized in that the separated solid phase of the enriched iron-containing material is washed with a concentrated aqueous solution of sodium chloride before washing with an acidic concentrated sodium chloride solution, which is taken in an amount equal to the moisture content of the solid phase material. 5. The method according to claim 1, characterized in that the washing of the solid phase of the enriched iron-containing material is carried out with an acidic concentrated solution of sodium chloride with a pH of 1-2, at T: W = 1: 1.25.

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