RU2535254C1 - Method of complex processing of serpentine-chromite crude ore - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to a waste-free complex processing of serpentine-chromite crude ore. When processing the particulate starting material is mixed with concentrated sulphuric acid. Then roasting and cinder leaching is carried out. The roasting is carried out with adding carbon in an amount of 6.0-10.0 wt % of crude ore at a temperature of 750-800°C for 3 hours. The cinder after roasting is leached with water at S:L=1:2.5. The resulting suspension is filtered, the filtrate is evaporated to crystallise the heptahydrate magnesium sulphate. The precipitate after filtration is subjected to hydrocycloning for separating the fine fraction, containing oxides of iron, nickel, aluminium from coarse fraction containing chromopicotite and silica. The coarse fraction is leached with aqueous solution of sodium hydroxide to obtain an alkaline solution of silica and precipitate, which is washed and dried to obtain the chromite concentrate.

EFFECT: complete isolation of the silica component, while simultaneous waste-free complex recovery of valuable raw material components.

2 cl, 1 dwg, 8 tbl, 9 ex

Description

The invention relates to a hydrometallurgical complex processing of unconventional types of raw materials - serpentinite and serpentinite dumps of waste rock in chrysotile asbestos and chromite deposits, in particular to the processing of serpentine-chromite ore raw materials to produce high-purity silicon dioxide (analogue of “white carbon black”), heptahydrate, magnesium sulfate chromite concentrate of other high quality inorganic substances.

When processing natural or technogenic raw materials, which include silica (SiO ₂ ) or silicon dioxide in the form of silicic acid (SiO ₂ × nH ₂ O), its silica component has traditionally been considered as a ballast and difficult to recycle part. At the same time, highly dispersed amorphous silicon dioxide, which is produced on the basis of acid processing of expensive “liquid” glass, is used in large quantities in various industries. There are a number of minerals: nepheline, eudialyte, feldspar, olivine, serpentine, etc., the acid and alkaline decomposition of which is accompanied by the transfer into the solution of not only metal salts, but also silica in the form of silicic acid. Therefore, the processing of this type of raw material is an urgent problem, because it allows you to get high-quality silicon dioxide, widely used in a number of industries: electronic, bus, chemical, perfumery, etc., as well as for producing silicate materials with unique properties: optical fibers (devices for directional transmission light energy), semiconductors, additives to improve the physical and mechanical properties of polymers and rubbers, etc.

1. There is a method of complex processing of waste from the Tuvaasbest plant, representing serpentinites containing up to 80% silicon and magnesium oxides. The content of the main components, depending on the type of serpentinite, ranges from,% wt: 35-40 MgO; 35-40 SiO ₂ ; 5-6 H ₂ O; 5-20 Fe _total ; 1-2 Cr, Ni, Al, etc. The main associated minerals are: asbestos, chromite, magnetite and other minerals.

The essence of this invention is as follows: pre-crushed material, particle size up to 0-0.15 mm, decompose 20-50% sulfuric acid. The suspension is filtered, the precipitate of amorphous silica and undecomposed magnetic minerals and magnetite is subjected to magnetic separation with the release of a concentrate of magnetite and chromite, as well as pure silicon oxide. For selective purification of the solution from sulfates of Fe, Cr, Ni, etc., they were precipitated using sodium hydroxide at a pH of 8–9 and a temperature of 60–80 ° C with preliminary addition of the required amount of hydrogen peroxide for oxidation of Fe ²⁺ , Ni ^{2 +} and Cr ²⁺ . Magnesium from the purified solution was precipitated in the form of hydromagnesite. Precipitation was carried out with a solution of soda at a temperature of 60-80 ° C. The precipitate was well filtered. After drying, the precipitate was calcined at a temperature of 800 ° C to obtain pure magnesium oxide (MgO) with an impurity content of from 0.005 to 0.1%.

Stock solutions of sodium sulfate obtained after the precipitation of hydroxides were treated with milk of lime with the release of pure calcium sulfate (CaSO ₄ × nH ₂ O), from which, after drying and calcination, pure gypsum (CaSO ₄ × 0,5H ₂ O) was obtained, widely used in medicine. Pure silicon oxide remaining after separation of magnetite and chromite from the precipitate was dried and calcined. The resulting product, the so-called "White soot", containing up to 95-99% SiO _2, is widely used in the production of plastics and rubber products. [one]

The developed technology for the integrated processing of serpentinites has been tested on a pilot scale. As a result of processing, the following were obtained: magnesium oxide, silicon dioxide, gypsum gypsum (CaSO ₄ × 0.5H ₂ O), Fe-Ni-Cr-concentrate.

The disadvantages of this method are:

- the use of this invention requires cumbersome hardware when conducting numerous filtering operations generated in the process of pulps;

- the claimed method is not waste-free, because it forms semi-aquatic gypsum, whose reserves grow faster than its needs, especially when processing apatite raw materials;

- this invention is possible only when using fairly expensive reagents, such as caustic alkali, sodium carbonate, hydrogen peroxide.

2. A known method of processing serpentine, according to which an aqueous suspension of finely divided mineral, with a ratio of T: W = 1: 1, is treated with concentrated sulfuric acid (ρ = 1.84 g / cm ³ ). The resulting mass is diluted with water and filtered. The resulting solution of magnesium sulfate is subjected to evaporation, crystallization and drying. The finished product is hemihydrous magnesium sulfate MgSO ₄ × 7H ₂ O. [2]

The disadvantage of this method is the high cost of concentrated sulfuric acid for leaching and the need to use processes that pursue very opposite goals (dilution, evaporation and drying).

3. A known method of processing silicate raw materials, in particular nepheline concentrate - (Na, K) Al SiO ₄ , including: decomposition of raw materials with sulfuric or hydrochloric acid, 5.0-30.0% concentration, filtering the suspension, heat treatment (dehydration) of the filtrate at 80-300 ° C, purification of the dehydrated product from impurities by leaching with hot water or a weakly acid solution, filtering the suspension and separating silicon dioxide from the liquid phase, drying and packaging of the finished product. [3] The finished product is characterized by good physicochemical properties: a large specific surface area (less than 100 m ² / g) and a high content of silicon dioxide (not less than 90%).

The disadvantage of this method is that it is suitable for the processing of raw materials that are readily degradable by weak solutions of mineral acids (5.0-30.0% concentration), such as nepheline, eudialyte, feldspars and other minerals, with the formation of soluble in water, sodium or potassium silicates, and cannot be used in the processing of serpentine-chromite ore mixtures, since the minerals included in its composition (olivine, pyroxene, forsterite, etc.) cannot be opened with such weak solutions.

The closest in technical essence analogue is a method of complex processing of serpentine-chromite ore raw materials. [four]

The method is as follows: the natural serpentine-chromite ore mixture is crushed to a particle size of less than 2.0 mm and leached with mineral acids (sulfuric 40-42% H ₂ SO ₄ or hydrochloric 10-20% HCl) at a temperature of 60-80 ° C in the ratio T: W in reaction zone 1: (2.5-4.0) for 1-2 hours until residual acidity in suspension (4.0-6.0 g / l H ₂ SO ₄ or 1.0-3, 0 g / l HCl). After that, the suspension is filtered. The filtrate solution of sulfates (chlorides) of magnesium, iron, aluminum, manganese is neutralized in 2 stages: to pH = 7.0-8.0 in order to precipitate hydroxides Fe ³⁺ , Al ³⁺ , Cr ³⁺ , Mn ^2+, and pH = 9.0-11.0 to obtain magnesium hydroxide.

The neutralization is carried out with a solution of concentrated soda.

Modified iron oxide pigments are obtained from a mixture of hydroxides Fe ³⁺ , Al ³⁺ , Cr ³⁺ , Mn ²⁺ after calcination, and periclase from Mg ²⁺ hydroxide.

To obtain high-purity silicon dioxide free of impurities of chromite, pyroxene and other minerals, an insoluble precipitate - cake 1, obtained after acid leaching of the ore mixture and containing a mixture of amorphous silica and insoluble minerals (chromite, pyroxene, etc.), is washed with water from water-soluble salts, (sulphate or chloride), dried at 105-110 ° C, calcined at a temperature of 350-600 ° C for 2 hours to dewatering cake, dehydrated silica (hydrogel SiO ₂ · nH ₂ O) and destruction of the structure of amorphous silica poskim lku silica after such treatment acquires an increased ability to dissolve in alkali.

Next, the precipitate (cake 1) is treated with a solution of sodium hydroxide (concentration of 140-180 g / l NaOH) at a temperature of 50-70 ° C and a ratio of T: W = 1: 4. The suspension is filtered, the insoluble residue is a chromite concentrate, washed from impurities, dried and packaged. The finished product contains at least 50-51% Cr ₂ O ₃ .

The filtrate after separation from chromite concentrate (the so-called "liquid glass") is treated with hydrochloric acid. The suspension is filtered, the precipitate (SiO ₂ ) is washed with hot water, dried at 105 ° C, calcined at 900 ° C and packaged.

The finished product is characterized by a high content of silicon oxide, not less than 98.30-99.99%.

The considered method of complex processing of magnesium-chromium-containing raw materials is ineffective and cannot be considered waste-free, because after the deposition of metal hydroxides Mg, Fe, Al, Cr, Ni, etc., the system is overflowed with weakly concentrated solutions of sodium sulfate (or chloride). A large amount of heat will be required to evaporate and dispose of such unclaimed salts.

In addition, the processing of metal hydroxides Mg, Fe, Al, Cr, Ni, etc. by calcining at high temperatures with the subsequent production of periclase and modified iron oxide pigments is also associated with high heat consumption.

The technical task of the claimed invention is the development of a cost-effective non-waste method for the integrated processing of serpentine-chromite ore raw materials, providing the maximum selective extraction of valuable components (magnesium, chromium, nickel, iron) and obtaining from any serpentinite ore mixtures of highly dispersed silicon dioxide or high-purity "liquid glass". The technical result of the application of this invention is to ensure the complete separation of the silica component from the raw material while simultaneously comprehensively extracting the valuable components of the raw material, which in turn will expand the scope of waste-free use of poor ore mixtures.

The technical result is achieved due to the fact that the ore mixture treated with concentrated sulfuric acid is calcined at 750-800 ° C in the presence of a reducing agent - carbon and leached out with water. The resulting suspension is filtered; the filtrate, consisting of magnesium sulfate, evaporates and crystallizes. The precipitated crystals of heptahydrate magnesium sulfate are washed, dried at 110 ° C and, as a finished product, are packaged. Insoluble precipitate (cake) is sent to hydrocyclone. A light (thin) fraction of Fe, Ni, Al oxides enters the sump and then for drying and enters the charge in the form of an iron oxide product. A large fraction consisting of mineral chrompicotite and amorphous silicon oxide is sent to leach caustic soda with a concentration of 150 g / l NaOH. The suspension is filtered. The precipitate - chromite concentrate - is washed, dried and packaged, as well as the filtrate - the so-called "Liquid glass", which is a sought-after high-quality product.

The method is as follows (see. The basic technological scheme of complex processing of serpentinite).

Natural serpentine-chromite ore (mineral and chemical compositions see Table 1) is crushed to a particle size of 0-0.2 mm, mixed with concentrated sulfuric acid (93.0% H ₂ SO ₄ in a ratio of 100-116 kg of H ₂ SO ₄ per 100 kg of ore), add 5.0-10.0% carbon (coke, soot, bitumen) to the mass of ore and calcine at 750-800 ° C for 2 hours. At these temperatures, the sulfates Fe ²⁺ , Fe ³⁺ , Al ³⁺ , Cr ³⁺ , Ni ⁺ that are part of the acidic mixture decompose into metal oxides and oxides of sulfur and carbon, and silica acquires an increased ability to filter and dissolve in alkalis.

The flue gases from the kiln after purification from SO ₃ , SO ₂ and CO ₃ are emitted into the atmosphere, and sulfur oxides are used to produce sulfuric acid.

The chemical and mineralogical composition of the undecomposed sludge after water leaching (acid cake), see table 2.

The calcined acid serpentinite mixture (cinder) is leached with hot (up to 80 ° C) water for 30-45 min at a ratio of T: W = 1: 2.5, the pulp is filtered. Metal oxides remain in the precipitate, and the filtrate containing magnesium sulfate without impurities is evaporated and crystallized. Precipitated crystals of heptahydrate magnesium sulphate are dried and packaged. The quality of the finished product - heptahydrate magnesium sulfate MgSO ₄ · 7H ₂ O see table 3.

The remaining cake, consisting of undecomposed minerals (chrompicotite, amorphous silica) and metal oxides, is washed with hot water, the washing water is sent to the beginning of the process for processing the acid serpentinite mixture, and the cake is sent to hydrocyclone, where particles are separated into fractions - 40% fine s particle sizes less than 40 microns and 60% large with particle sizes of 40-200 microns.

The fine fraction (consisting of oxides,% mass .: serpentinite - 2.5; Al ₂ O ₃ - 3.4; colloidal SiO ₂ - 65.9; Fe ₂ O ₃ - 28.0; chromite - 4.0) is sent into the sump. After sludge, the precipitate (iron oxide product) is sent for drying to obtain modified iron oxide pigments with a wide range of shades or mixed with cement in order to obtain colored concrete.

A large fraction consisting of undecomposed minerals: chrompicotite, silica, and other minerals is sent to leach amorphous silica with a solution of caustic soda (15.0% NaOH) for 15-30 minutes. The suspension is filtered. The precipitate, a mixture of undecomposed minerals and chrome picotite, is washed with hot water and dried at 105 ° C.

Mineralogical and chemical compositions of the coarse sediment fraction after leaching with a 15.0% NaOH solution, see table 3.

The finished product, a chromite concentrate, is washed with hot water to a minimum content of Na ion impurities, dried at 110 ° and packaged in bags. The quality of the finished product meets the requirements of TU (see table 8).

The filtrate, the so-called “Liquid glass”, free from mechanical impurities, is packed into barrels (cans) or sent for further processing to obtain high-purity silicon dioxide. The quality of "liquid glass" corresponds to GOST 13078-81 (see table 7).

The operation of firing an acid serpentine-chromite mixture has a significant effect on the alkaline leaching of a large fraction after hydrocyclone, especially on the rate of filtration of an alkaline suspension. So, when filtering a suspension after alkaline leaching of a calcine calcined at a temperature of 390 ° C, a substantially low filtration rate of 0.38 cm / min is observed, compared with a filtration rate of 2.24 cm / min in a similar process at a calcination temperature of 750 ° C (see table 5).

The filtration rate of the alkaline suspension was estimated by the volume of filtrate passing through the filter area per unit time (cm / min).

The effectiveness of the developed technology and the selected process parameters: the temperature of roasting the acid mass of the ore, the duration of the water leaching of the cinder, the T: W ratio, and the carbon concentration in the calcined mixture are judged by the amount of harmful impurities that have passed into the solution (magnesium-containing filtrate) - sulfates Fe, Ni, Al (cm Table 4).

The lower the content of impurity metals in the filtrate after water leaching of the cinder, the more efficient the technology being developed (see examples).

Example 1. The processing of poor serpentine-chromite ore mixture was carried out according to the technology of the prototype.

The natural ore mixture (mineralogical and chemical compositions see Table 1) is crushed to a particle size of less than 2.0 mm and leached with 40-42% sulfuric acid at 60-80 ° C in the ratio T: W = 1: (2.5-4 , 0) within 1-2 hours to residual acidity in a suspension of 4.0-6.0 g / l H ₂ SO ₄ . After that, the suspension is filtered.

The filtrate solution of magnesium, iron, aluminum and nickel sulfates is neutralized in the 2nd stage: to a pH of 7.0-8.5 in order to precipitate the hydroxides Fe ³⁺ , Al ³⁺ , Cr ³⁺ , Ni ²⁺ and to pH = 9.0-11.0 to obtain magnesium hydroxide. Neutralization is carried out with a 50.0% soda ash solution.

Modified iron oxide pigments are obtained from Fe ³⁺ , Al ³⁺ , Ni ²⁺ hydroxides, and MgO from hydroxide Mg ²⁺ (in any modification, depending on the heat treatment).

To obtain high-purity silicon dioxide free of impurities of chromite, pyroxene, and other minerals, an insoluble precipitate, cake 1, obtained after sulfuric acid leaching of the ore mixture and containing a mixture of amorphous silica and insoluble minerals (chromite, pyroxene, chlorite, etc.), is washed from water-soluble salts (sulfates), dried at 105-110 ° C, calcined at 350-600 ° for 2 hours in order to dehydrate the cake and destroy the structure of amorphous silica. Next, cake 1 is treated with a solution of caustic soda (with a concentration of 140-180 g / l NaOH) for 15-30 minutes, at 50-70 ° and the ratio T: W = 1: 4 to a NaOH content in the suspension of at least 40 g / l . The suspension is filtered, an insoluble residue - a chromite concentrate - is washed from impurities with hot water, dried at a temperature of 105-110 ° C and packaged. The finished product contains at least 50.0% Cr ₂ O ₃ , after separation of the chromite concentrate, the so-called "Liquid glass", packaged as a finished product or sent for further processing.

However, this technology has not found wide application, since it has a significant drawback - it is not waste-free, because the system is overfilled with a large amount of a low concentration solution of sodium sulfate (22.4%). So, for example, upon obtaining 326 kg of hydroxides Mg ²⁺ , Fe ³⁺ , Al ³⁺ , Cr ³⁺ and Ni ^{2+ by} leaching from 100 kg of serpentine-chromite ore 272 kg of 40% sulfuric acid, 760 kg of sulfate solution is formed sodium (22.4%) with a density of 1.376 g / cm ³ . The evaporation of such an amount of sodium sulfate will require large expenditures, and sodium sulfate itself is not much in demand.

Example 2. Natural serpentine-chromite ore (mineralogical and chemical compositions see table 1) are crushed to particle sizes 0-0.2 mm, mixed with 116 g of concentrated 93.0% H ₂ SO ₄ sulfuric acid, calcined at 390 ° C for 5 hours and leached with water at a ratio of T: W = 1: 5 (see table 4). The density of the suspension of 1.17 g / cm ³ . The suspension is filtered, the filtrate is evaporated to crystallize heptahydrate magnesium sulfate (composition of the filtrate, see table 4). Kek sent for hydrocyclone. The fine fraction is sent to the sump, filtered and packaged as a finished product. A large fraction, consisting of chrompicotite, silicon oxide, and other minerals, is sent to the leaching of silica with a solution of sodium hydroxide (150 g / l) with a ratio of m: w = 1: 2-2.5 for 15-30 minutes. The suspension is filtered at a speed of 0.38 cm / min (see table 5). Sediment - a mixture of chrompicotite and undecomposed minerals is washed with hot water, dried at 110 ° C and packaged. The finished product - chromite concentrate - contains 35.9% Cr ₂ O ₃ (see table 5). The filtrate is an alkaline solution of silica, the so-called "Liquid glass", packaged or sent for further processing.

The efficiency of the complex processing of chromite-serpentinite compounds was evaluated by the effect of the firing temperature on the content of harmful impurities in the solution (filtrate) after water leaching of the calcine - undecomposed sulfates at the given firing temperature and, accordingly, converted to a magnesium-containing solution (filtrate): iron, nickel and aluminum (see table 4), as well as the rate of filtration of the suspension after alkaline leaching of silica (see table 5).

Table 4 and 5 show the results of op.1. Obviously, the high extraction of impurity metals in a magnesium-containing solution due to their sulfates not decomposed at a temperature of 390 ° C (Fe ²⁺ , Fe ³⁺ - 32.0%; Ni ²⁺ - 46.3% and Al ³⁺ - 36, 3%), and low parameters of the process of alkaline leaching of silicon dioxide (suspension filtration rate - 0.38 cm / min, the yield of chromite concentrate - 47.5% and the content of Cr ₂ O ₃ in the concentrate - 35.9%) indicate that firing at this temperature is not very effective.

Example 3. The processing technology of the serpentine-chromite mixture, mineralogical and chemical compositions are similar to example 2.

An acidic serpentinite batch is calcined at 700 ° C for 3 hours and leached with water at a ratio of T: W = 1: 2.5 (see table 4, option 2). Table 4 shows that the extraction of harmful impurities (sulfates) decreases, however, remains quite high (the extraction of sulfates in the filtrate was,%: Fe _total - 15.7; Ni - 35.6 and Al - 0.03).

Example 4. The processing technology of mineralogical and chemical compositions, the concentration of sulfuric acid is similar to Example 3. The firing temperature was 800 ° C, the duration was 3 hours, the ratio T: W = 1: 2.5, the density of the suspension was 1.29 g / cm ³ (see option 4). The concentration of harmful impurities continues to decrease, and the extraction of impurities in a magnesium-containing solution is,%: Fe _total - 8.1; Ni - 31.3; Al is 0.03.

Example 5. All process parameters are similar to example 4, only 6.0% of the reducing agent — coke — is introduced into the charge (see table 4, option 6). The filtration rate of the alkaline suspension was 2.24 cm / min, the yield of chromite concentrate was 85.2%, and the content of Cr ₂ O _{3 was} 51.4% (see table 5, option 6). Extraction into the magnesium-containing solution of harmful impurities significantly decreased,%: Fe _total - 4.1; Ni - 13.1; Al is 0.02.

Example 6. All process parameters are similar to example 5. The firing duration is 2 hours, the extraction of impurities,%: Fe _total - 4.2; Ni - 14.4; Al - 0.02 (see table 4, op. 7).

Example 7. All process parameters are similar to example 6. The firing time is 1 hour, the extraction of impurities is increased,%: Fe _total - 8.4; Ni - 23.1; Al - 0.02 (see table 4, op. 8).

Example 8. All process parameters are similar to example 7. The firing duration is 3 hours, T: W = 1: 2.5, the coke content is 10.0%. Extraction of impurities in the solution is minimal,%: Fe _total - 1.1; Ni - 3.8; Al - 0.02 (see table 4, op. 9).

Example 9 (op. 10). All process parameters are similar to example 8, the content of the reducing agent (coke) is 15.0%. Extraction of harmful impurities in the filtrate,%: Fe _total - 1.0; Ni - 3.6; Al is 0.02.

Thus, on the basis of the experiments we can draw the following conclusions.

1. The developed method for the integrated processing of poor magnesium-chromium-containing ore mixtures is waste-free, since it allows almost 100% utilization of the minerals included in the mixture to produce high-quality inorganic substances that meet the requirements of GOST and TU.

2. The optimal technological process parameters are:

- The particle size of the ore mixture is 0.0-0.2 mm;

- The ratio of ore mixture and concentrated sulfuric acid (93.0% H ₂ SO ₄ ) - 1: 1.16;

- The temperature of regenerative firing - 700-800 ° C;

- Duration of firing - 3.0 hours;

- With water leaching of acid cinder, the ratio T: W = 1: 2.5;

- The concentration of the reducing agent (carbon) is 10.0%.

3. The temperature, duration and concentration during firing below optimal values does not contribute to the complete decomposition of mineral raw materials.

4. The temperature, duration and concentration of carbon during firing above optimal values will lead to a significant increase in the cost of the process.

Table 1 Mineralogical and chemical compositions of serpentine-chromite ore raw materials Density γ _t = 2.02 g / cm ³ No. Mineralogical composition Chemical composition Name of materials Content% Name of components and their content,% Al ₂ O ₃ MgO SiO ₂ Fe ₂ O ₃ Cr ₂ O ₃ Nio ppp one Serpentine 63.0 - 27.6 26.3 3.95 - 1,0 2 Chromicotitis 13.0 0.95 1.3 0,065 3.25 6.04 - 3 Forsterite (olivine) 15.0 0.19 6.5 6.85 0.24 - - four Chlorite 3.0 0.4 0.9 0.785 0.04 - - 5 RAF 6.0 - - - - - - Total: 100.0 1,54 36.3 34.0 7.48 6.04 1,0 13.64

table 2 Mineralogical and chemical compositions of undecomposed sludge after water leaching of the calcined ore mixture (cinder) Mineralogical composition,% Chemical composition, % Chrompicotitis - 23.0 Cr ₂ O ₃ - 10.2 Forsterite - 2.0 SiO ₂ - 64.0 Chlorite - 2.0 Al ₂ O ₃ - 2.05 RAF (SiO ₂ ) - 73.0 Fe ₂ O ₃ - 4.43 MgO - 3.17 checkpoint - 15.75

Table 3 Mineralogical and chemical compositions of the coarse sediment fraction after leaching with sodium hydroxide solution (NaOH - 15%) Mineralogical composition Chemical composition Name of components Content% Name of components Content% Chromicotitis 85,2 Cr ₂ O ₃ 51,4 Forsterite 7.4 Al ₂ O ₃ 10.3 Chlorite 7.4 Fe ₂ O ₃ 22.3 MgO 10.0 SiO ₂ 3.2 ppp 2,8

Table 5 The effect of firing temperature on the technological parameters of alkaline leaching No. op. Firing temperature, ° C Filtration rate
cm / min Chromite yield
concentrate,% The content of Cr ₂ O ₃ in the chromite concentrate,% one 390 0.38 47.5 35.9 3 750 2.24 82.5 50,2 6 800 2.24 85,2 51,4

Table 6 Properties of heptahydrate magnesium sulfate MgSO ₄ * 7H ₂ O GOST 4523-77 The name of indicators mark The quality of the claimed technology H.Ch. H 1. Mass fraction of MgSO ₄ * 7H ₂ O,%, min 99.5 90.0 99.6 2. Mass fraction of insoluble substances,%, max 0.002 0.002 0.002 3. Acidity, content of H ₂ SO ₄ ,%, max 0.002 0.002 0.002 4. The content of glands Fe _total ,%, max 0.002 0.002 0.002

Table 7 The quality of "liquid glass" GOST 13078-81 Name of components A B Quality by developed technology Content% Content% 1. Thick yellow or gray liquid without mechanical impurities visible to the naked eye Thick yellowish liquid without mechanical impurities 2. Mass fraction of silicon dioxide SiO ₂ , not less 22.7-24.6 24.3-31.9 34.6-36.0 3. Mass fraction of iron oxide Fe ₂ O ₃ , aluminum oxide Al ₂ O ₃ , not more than 0.25 0.25 0.1

Table 8 The quality of chromite concentrate TU 14-9-219-81 The chemical industry consumes ores and concentrates with a content of at least 45%, of any physical condition, but preferably powder, loose and fine (up to 10.0 mm). No. Quality indicators Norm in% TO TU The quality of the concentrate according to the developed technology one Physical state Loose powder with particle size up to 10.0 mm Fluffy black powder with a particle size of less than 2.0 mm 2 The content of Cr ₂ O ₃ ,% (average) 49.0 51,4 3 The content of SiO ₂ ,% (average) 8.0 3.2 four The content of FeO,% (average) 14.5 4.2 5 Moisture, no more 5,0 3.0

Literature

1. Integrated waste management of the Tulaasbest plant. Manzyrykchy Kh.B., Kaminsky Yu.D., Polugrudov A.V. Pat. RF №1797747, 04/08/91. Pat. RF №2038301, 6 CO1F 5/06, publ. 06/27/95. Bull. Number 18.

2. Pozin M.E., Kopylev B.A. et al. Auth. testimonial. 586125. USSR Patent 12/30/1971

3. Patent RU No. 2179527, IPC C01B 33/187, publ. 02/20/2002

4. Patent RU No. 2344076.

Claims (2)

1. The method of complex processing of serpentine-chromite ore raw materials, comprising mixing the crushed feedstock with concentrated sulfuric acid, calcining and leaching the cinder, characterized in that the firing is carried out at a temperature of 700-800 ° C for 3 hours, the leaching of the cinder is carried out with water at a ratio T: W = 1: 2.5, the resulting suspension is filtered, the filtrate is evaporated to crystallize heptahydrate magnesium sulfate, and the precipitate is subjected to hydrocyclone to separate into a fine fraction containing oxides of iron, nickel, aluminum, and upnuyu fraction containing hrompikotit and silica, wherein the coarse fraction is leached with an aqueous solution of sodium hydroxide to obtain an alkali solution and silica sediment, which was washed and dried to obtain chromite concentrate. 2. The method according to claim 1, characterized in that the firing is carried out with the addition of carbon in an amount of 6.0-10.0 wt.% From ore raw materials.

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