RU2318888C1 - Magnesium extraction method from natural silicon-containing materials - Google Patents

Abstract

FIELD: processes for extracting magnesium from natural silicon -containing materials and waste material such as serpentinite.

SUBSTANCE: method comprises steps of disintegrating initial solid material; leaching it and washing leached residue. Disintegration is performed till fraction size 0.4 + 0.1 mm. Leaching of disintegrated material and washing of leached deposit are realized by countercurrent in uprising vertical flows of hydrochloric acid solution and water at heating and applying reciprocation type oscillations with intensity 800 - 1000 mm/min. Transportation of leached deposit to washing operation is realized by means of hydraulic transport with use of water. At unloading leached deposit from vertical flow, volume of water equal to volume of unloaded deposit is guided for mixing with initial water used for hydraulic transport.

EFFECT: improved efficiency of magnesium extraction, possibility for lowering dilution degree of chlorine-magnesium solution, reduced cost of concentration by evaporation and of decreased loss of valuable components at washing.

4 cl, 1 dwg, 2 tbl, 1 ex

Description

The invention relates to the field of extraction of magnesium from natural silicon-containing materials and waste, such as serpentinite.

A known method of extracting magnesium from serpentinite residues (patent RU No. 2233898, publ. BI 22, 08/10/04), including the leaching of magnesium with a solution of hydrochloric acid when heated, multi-stage neutralization to clean the solution of magnesium chloride, separation of solid and liquid phases and washing the resulting draft.

The disadvantage of this method is that it is characterized by a low efficiency of magnesium extraction and does not imply a complex processing of the feedstock to produce iron-nickel concentrate and commercial products from silicon-containing leached sludge.

The closest in its technical essence and the achieved effect to the proposed is the method (patent RU No. 2237111, publ. BI 27, 09/27/04) extraction of magnesium from silicon-containing materials, which includes the operation of grinding the feedstock, leaching of magnesium and impurities with hydrochloric acid solution heating to obtain a suspension containing a magnesium chloride solution, separation of the magnesium chloride solution and the precipitate, and washing it from soluble substances.

The disadvantage of this method is that when it is used, direct-flow interaction of the solid material and the hydrochloric acid solution in the leaching operation is performed, in which the extraction efficiency of magnesium is low, and the dilution of the commercial chlorine-magnesium solution is significant, which requires additional energy costs for the subsequent operation of the evaporation of the commodity solution . The disadvantage is also that in the operation of washing the precipitate increases the loss of magnesium and acid due to the lack of efficiency of the process.

The technical result of the invention is a highly efficient extraction of magnesium from natural ore materials, reducing the phenomenon of dilution of a chlorine-magnesium solution and reducing the cost of evaporation before subsequent operations, as well as reducing the loss of valuable components during washing.

The technical result is achieved by the fact that the solid material is crushed to a particle size of -0.4 + 0.1 mm, after which the leaching and washing of the precipitate is carried out countercurrent in ascending vertical flows of a solution of hydrochloric acid and water when applying reciprocating oscillations, while after leaching, unloading sediment and supplying it for flushing with the help of a hydrotransport system.

The problem is also solved by the fact that the reciprocating vibrations are carried out at an intensity of 800-1000 mm / min, and also by the fact that water is used for hydrotransport, and when unloading leached sediment from a vertical stream, a volume of water equal to the amount of sediment discharged is sent into circulation mixing with the source water used for hydrotransport.

Highly efficient extraction of magnesium from a solid material can be carried out only under conditions of countercurrent interaction of a solid material and a solution of hydrochloric acid, which under equal conditions, in comparison with direct-flow interaction, allows to achieve a greater extraction of magnesium into the solution and to obtain a strengthened solution of a higher concentration. However, in practice, the organization of countercurrent interaction of a solid material and a hydrochloric acid solution encounters considerable difficulties. This is evidenced by the lack of technical solutions for the organization of counterflow leaching in all known patents, as well as specific examples of industrial implementation of this leaching method. Nevertheless, difficulties can be overcome by using the technical solutions we offer. In particular, to organize a highly effective countercurrent interaction, for example, serpentinite and a hydrochloric acid solution during leaching, it is proposed to grind the starting material to a well-defined particle size of -0.4 + 0.1 mm. With such a coarseness of the crushed material, it is possible to provide countercurrent motion of the solid and liquid phases and a given residence time of the solid material in the vertical flow. A well-defined size of grinding of solid material is the main condition for leaching and washing in countercurrent mode in ascending flows of a solution of hydrochloric acid (during leaching) and washing water (during washing).

A single inventive concept with the organization of leaching and washing processes in countercurrent mode in vertical flows is also associated with technical solutions to the methods of transporting leached sludge to the washing operation and its discharge from the vertical leaching stream. Both countercurrent interaction of solid particles and acid, and the proposed methods of transportation and unloading, allow achieving maximum efficiency of magnesium extraction, minimal dilution of commercial chlorine-magnesium solution, maximum use of acid, and reduction of magnesium and acid losses during washing.

Obviously, when unloading leached sludge from the bottom of the vertical stream, unless special measures are taken, a certain amount of liquid is discharged with the sludge, which is an 18-19% hydrochloric acid solution (the yield of acid with sludge is about 7.5% of the total acid entering the leaching operation). This amount of acid is not used in the leaching process, but is a transporting liquid for leached sludge to the washing operation. Such a solution is ideal when only a solid precipitate is discharged from a vertical leaching stream without a liquid phase and, accordingly, without acid. In this case, all the source acid entering the vertical stream would be used for the reaction with the solid material, and would not be spent on transporting the leached precipitate. This problem can be solved if sludge is unloaded from a vertical stream into a hydrotransport tank filled with water, and water displaced during unloading of sludge, the volume of which is equal to the volume of sludge discharged, is put into circulation for mixing with the source water used to organize hydrotransport. With this method of removing the water displaced by the sediment from the hydrotransport vessel, it is possible to avoid the entry of water into the vertical leach stream and thereby to avoid dilution of the commercial chlorine-magnesium solution. With this method of sludge unloading, only a small amount of acid passes from the bottom of the vertical stream to the hydraulic transport tank, that is, almost all of the incoming acid is used for leaching. Thus, when implementing the proposed method of hydrotransport and sludge unloading, it is possible to achieve the maximum efficiency of the leaching process due to the full use of acid, eliminating the dilution of the magnesium chloride solution and the receipt of the minimum amount of acid in the sludge washing operation.

Highly effective methods of leaching magnesium and washing the precipitate can be achieved only with well-defined recommended numerical values of the technological parameters of the process. So, the recommended indicators of fineness of grinding of the initial serpentinite are -0.4 + 0.1 mm. If the serpentinite particle size exceeds 0.4 mm, the hydrodynamic effect of the ascending oscillating vertical flow is not enough to bring solid particles into suspension. In addition, with an increase in grinding fineness of more than 0.4 mm, the kinetics of the process of leaching of magnesium from the solid phase slows down. When reducing the size of grinding of solid material less than 0.1 mm, fine particles are formed, the sedimentation rate of which is significantly reduced. As a result of this, the specific productivity of the leaching and washing processes is reduced so much that an unreasonably large apparatus will be required during the industrial implementation of these processes.

To increase the efficiency of the processes, indicators of the intensity of the reciprocating oscillations - 800-1000 mm / min, have quite definite values. When the vibration intensity is less than 800 mm / min, the mixing efficiency of the solid particles and the upward flow of the acid solution decreases and, accordingly, the efficiency of magnesium extraction, especially from the largest particles, decreases. With an increase in the intensity of vibrations of more than 1000 mm / min in industrial-sized apparatuses, the longitudinal mixing coefficient increases by more than 5 times, which leads to a decrease in the efficiency of leaching and washing processes.

The proposed method is as follows. For the practical implementation of the method, the installation shown in the drawing is used.

The installation includes vertical column apparatuses 1 leaching and 2 leaching, capacity of the original acid 3, washing water 4 and a tank 5 for water used for hydrotransport leached sludge. Hydrotransport tanks 6 and 7 are connected to vertical column apparatuses 1 and 2. Centrifugal pumps are used to transport material streams: 8 - supply of hydrochloric acid solution, 9 - for flushing water, 10 and 11 - water supply for hydrotransport, respectively, leached and washed precipitation. To create reciprocating oscillations, pulsation chambers 12 and 13 connected to pulsators 14 and 15 are connected to column apparatuses 1 and 2. Column apparatuses are sectioned by contact plates. The initial acid is heated to the required temperature of 95-100 ° C by steam from the steam generator 16 in the ejector 17. The hydrotransport tanks 6 and 7 are equipped with a valve system 18, 19, 20, 21, as well as 22, 23, 24 and 25. The leached sediment from the hydrotransport tank 6 is transported to the apparatus 2 through a pipe 26 through an intermediate sump 27, which contains the entire volume of sludge discharged from the hydrotransport tank 6. The washed sludge is transported through pipe 28. Automatic control of the leached sludge discharge process and from the apparatus 1 is carried out using level sensors 29, 30 installed externally in the upper part of the pulsation chamber 12, and sensors 31 and 32 installed outside the hydrotransport vessel 6. Correspondingly, level gauges 33, 34, 35 and 36 are used for the washing apparatus 2. To maintain a high temperature of leaching and washing, the column apparatuses 1 and 2 are thermally insulated, the equipment is made in a corrosion-resistant version. Temperature measurement in the column apparatus 1 and 2 is carried out using thermocouples 37 and 38.

The extraction of magnesium from solid material in the installation is as follows.

The starting solid material is crushed to a particle size of -0.4 + 0.1 mm and fed by a metering device of any type in dry form to the column apparatus 1, in which countercurrent leaching of serpentinite in an upward flow of hydrochloric acid solution occurs. The initial hydrochloric acid with a given flow rate from the tank 3 by centrifugal pump 8 is fed into the ejector 17, in which it is mixed with the steam generated in the steam generator 16, heated to a temperature of up to 100 ° C and then enters the lower part of the apparatus 1. In the column apparatus 1, solid precipitated particles are in contact with a solution of hydrochloric acid in the working part of a vertical apparatus, partitioned by contact plates, under the influence of reciprocating vibrations with an intensity of 800-1000 mm / min. The reciprocating oscillations are created by the pulsator 14 and transferred to the apparatus 1 through the pulsation chamber 12. Magnesium and other impurities contained in the feed — nickel, iron, calcium, cobalt, aluminum, and other elements that are discharged into the raw material — are leached from the solids as a result of leaching. the upper discharge, and magnesium depleted solid particles are deposited in the lower part of the column apparatus 1. To ensure high efficiency of magnesium extraction from solid particles in a vertical stream, it is necessary to provide a specified time rebyvaniya solid material in the column unit in the range of 2.5-3.0 hours. To this end, the entire working part of the column apparatus 1, partitioned by contact plates, is filled with accumulating sediment. When filling the column apparatus 1 with sediment, the boundary of oscillations in the pulsation chamber 12 is established between the upper 29 and lower 30 level sensors. When the boundary of the oscillations of the level sensor 29 reaches the command to open valves 18 and 19. When these valves are opened, leached sediment by gravity flows into the hydrotransport tank 6 filled with water, and the water from the hydrotransport tank 6, the volume of which is equal to the volume of discharge sediment, through the valve 19 is discharged into the tank 5. In this tank is water with a temperature of 80 ° C. To withdraw a limited amount of water equal to the amount of sludge discharged into the container 5, a calibrated washer is installed in the flanges of the valve 19, the hole diameter of which is determined by calculation. With such a discharge system, solid sediment particles with a minimum amount of acid enter the hydrotransport vessel 6 from the apparatus 1. When unloading leached sediment into the hydrotransport vessel 6, a limited amount of acid is captured in the form of film moisture, as well as moisture in the pores of solid particles. Water from the hydrotransport vessel 6 does not enter through the valve 18 into the apparatus 1, but in the form of a circulation stream under the action of a hydrostatic column is displaced into the vessel 5 with the source water. As a result of this, the initial acid does not dilute in the column apparatus above the valve 18. With the organization of such a discharge system, the concentration of hydrochloric acid in the water of the hydrotransport vessel 6 does not exceed 3-4 g / l, while the acid concentration in the lower part of the column 1 above the valve 18 is up to 200 g / l. As the sediment is unloaded from the column apparatus 1 into the hydrotransport vessel 6, the oscillation boundary in the pulsation chamber 12 drops to the level of the lower sensor 30, which gives the command to close the valves 18 and 19. As the hydrotransport vessel 6 is filled with sediment and reaches the sensor level 31 valves 20, 21 are opened sequentially to the command and the centrifugal pump 10 is turned on, which supplies heated water to the hydraulic transport tank 6. At the same time, the discharge system is blocked from sensors 29 and 30 to valves 18 and 19. In this case, the leached sludge from the hydrotransport vessel 6 is transported to the intermediate sump 27 and then to the column washing apparatus 2. When the sediment level in the hydrotransport vessel 6 decreases to the lower sensor 32, the centrifugal pump 10 is turned off, the valves 20 and 21 are closed, and the sediment discharge blocking is removed from the level sensors 29 and 30 to the valves 18 and 19. The hydrotransport vessel 6 is filled with water during transportation of the sediment. When the border reaches the oscillations in the pulsation chamber 12 level sensors 29 and 30 again, the unloading cycle is repeated. In the column apparatus 2, countercurrent washing of the sediment from acid traces in the upward flow of water is carried out with the application of reciprocating vibrations with an intensity of 800-1000 mm / min from the pulsator 15 through the pulsation chamber 13. The initial washing water with a temperature of 80 ° C is supplied to the lower part of the apparatus 2 from the tank 4 by a centrifugal pump 9 and after contacting with the sediment is discharged through the upper part of the apparatus 2 in the form of a washing solution, which is sent into circulation. The washed solid precipitate settles in the lower part of the column apparatus 2 and fills it. When the boundary reaches the oscillations in the pulsation chamber 13 of the level of the sensor 33, a command is issued to open the valves 22 and 23. In this case, the washed sediment is unloaded from the apparatus 2 into the hydrotransport tank 7 and the water leaves the hydrotransport tank 7 through the valve 23 and the calibrated washer into the tank 4. When the boundary reaches the oscillations of the sensor 34, the valves 22 and 23 are closed. When the sediment layer reaches the level of the sensor 35 in the hydrotransport vessel 7, the valves 24, 25 are opened sequentially, the centrifugal pump 11 is turned on and the discharge system from the sensors 33 and 34 of the valves 22, 23 is blocked. The water coming from the tank 4 transports the washed sediment through pipeline 28 to further processing and obtaining from it, for example, liquid glass, silicon tetrachloride and other valuable products. When the sediment layer is reduced to the level of the sensor 36, the centrifugal pump 11 is turned off, the valves 24 and 25 are closed, the lock is removed from the discharge system from the sensors 33 and 34, and the discharge cycle is repeated again.

Example

The process of extraction of magnesium from serpentinite, which is the tailings of the enrichment of raw materials used for the production of asbestos in Asbest in the Urals, is being carried out. The magnesium content in the feedstock is 24%. The sieve characteristics of the crushed material to a particle size of -0.4 + 0.1 mm are presented in table. one.

Table 1 Sieve characteristics of the initial serpentinite Particle size mm Content% +0.4 0.06 -0.4 + 0.315 0.02 -0.315 + 0.20 8.74 -0.20 + 0.14 48.83 -0.14 + 0.063 40.96 -0.063 1.39

The process of extracting magnesium by leaching and washing is carried out in accordance with the proposed technical solution in vertical flows in counterflow, which are implemented in experimental column apparatuses - in a leaching apparatus ⌀ 150 mm, a total height of 9900, a height of the working zone of 8800 mm and a washing apparatus ⌀ 100 mm, with a total height of 7000 mm and a height of the working area of 6000 mm. Reciprocating oscillations are created in the devices with a frequency of 26 counts / min and an amplitude of 35 mm (intensity of oscillations is 910 mm / min). Apparatuses and auxiliary equipment are made of steel-20 and coated inside with faolite, used as a corrosion-resistant material. Serpentinite is fed into the process with a dispenser at a rate of 30 kg / h. The initial 20% hydrochloric acid solution is heated by steam from a steam generator and is supplied to the lower part of the column leaching apparatus with a temperature of about 100 ° C and with a flow rate of 120 l / h. When heated by steam, the concentration of hydrochloric acid decreases from 20 to 18%. To prevent heat loss, the devices are thermally insulated from the outside. The working areas of the devices are partitioned by contact plates having a passage area of about 20%. The sectioning plates are made of faolite and installed in height at a distance of 100 mm from one another. The upper fortified chlorine-magnesium solution with an average excess content of free hydrochloric acid of 30 g / l is discharged in the upper part of the leaching apparatus. By means of valves ⌀ 32 mm, hydrotransport tanks with a volume of 9.4 l (⌀ 200 mm, H = 300 mm) are connected to the lower settling chambers of the column apparatus. Water intended for hydrotransport of leached sludge is supplied from a separate tank by a centrifugal pump, characterized by a pressure of 20 m of water. Art. and a flow rate of 1 m ³ / h. On the lines of water supply to hydrotransport tanks, water outlet when unloading sediments from them and transporting sediments, valves ⌀ _at 15 mm made of fluoroplastic are installed. The flushing apparatus uses the same auxiliary equipment and with the same technical characteristics as for the leaching apparatus. As a result of the leaching process, part of the solid material is dissolved in an amount of 58% of the original solid. Magnesium, iron, nickel, cobalt, chromium, calcium, aluminum and other impurities pass into the commercial solution in the form of chloride compounds. The precipitate remains mainly silicon dioxide. The sieve characteristics of the leached and washed sludge are practically unchanged, which indicates that the sizes of the solid particles remain the same, and only their structure changes with the formation of an intra-porous surface. From the leaching apparatus, the sludge is transferred via the hydrotransport system to an acid washing operation. The flow rate of washing water is about 2 m ³ per 1 ton of solid. Between valve flanges pos. 19 and 23, calibrated washers ⌀ _y = 0.7 mm are installed, the size of which is calculated by the equation

,

,

where Q is the water flow equal to the volume of discharged sludge, μ is the coefficient equal to 0.63, F is the cross-sectional area of the calibrated washer, N is the height of the pulp column in the column apparatus above the calibrated washers.

The results of the extraction of magnesium from serpentinite and washing the precipitate are presented in table. 2.

table 2 The results of the processes of countercurrent leaching of magnesium from serpentinite and countercurrent leaching of sludge in a column apparatus with pulsating mixing (the temperature of the initial hydrochloric acid solution is about 100 ° C, the magnesium content in the feedstock is 24%, the vibration intensity is 910 mm / min, the temperature of the wash water is 80 ° C, the temperature in the middle part of the leaching apparatus 98 ° C, in the upper part 95 ° C) Leaching Consumption of solid material, kg / h Specific load on solid material, t / m ² . day Consumption of 18% hydrochloric acid solution, l / h Specific acid consumption per 1 ton of solid, m ³ / t Acid solution upward speed, m / h The content in the fortified solution, g / l Content at the bottom of the leach apparatus The content of hydrochloric acid in the hydraulic transport capacity, g / l The amount of solid after leaching, kg The efficiency of the leaching process,% magnesium of hydrochloric acid suspensions magnesium precipitate,% hydrochloric acid, g / l sagnia in solution, g / l thirty 40 120 four 6.8 56.8 _~ 30 1,0 3.0 201 0.1 3.6 12.6 94.7

Continuation of the table. 2 RINSE Flushing water consumption, l / h Specific washing water consumption, m ³ / t solid The rate of upward wash water, m / h The specific load on the solid, t / m ² . day The acid content in the upper drain, g / l The magnesium content in the sediment,% PH in the moisture of the washed precipitate G: T ratio for hydrotransport Suspension content in the upper discharge, g / l The magnesium content in the moisture of the washed precipitate, g / l The amount of silicon dioxide in the sediment,% The washing efficiency,% 25 2.0 3.2 38.5 2.3 ^X) 3.0 about 5.0 1: 1 less than 0.1 not found 85 99.8 ^X) A certain amount of acid passes into the solution from the pores of the leached precipitate during the washing process.

From the data table. 2 it follows that in vertical flows during countercurrent interaction of serpentinite and an acid solution and subsequent washing of the leached precipitate, high rates of magnesium extraction (E = 94.7%) and washing efficiency (E = 99.8%) are achieved. Using the proposed leached sludge discharge and transportation system, it is obvious that almost all of the acid is used in the leaching operation. The hardened chlorine-magnesium solution is not diluted with water used for hydrotransport. The acid concentration in the lower part of the leaching apparatus and in the hydrotransport vessel are significantly different (201 and 3.6 g / l).

The proposed method for the extraction of magnesium from serpentinite is supposed to be implemented in industry for a newly designed enterprise.

Claims (4)

1. A method of extracting magnesium from silicon-containing materials, including grinding the starting material, leaching with a solution of hydrochloric acid when heated to obtain a strengthened chlorine-magnesium solution, separating the magnesium-chloride solution and the leached precipitate, and washing the precipitate with water, characterized in that the starting material is crushed to a particle size of -0.4 +0.1 mm, leaching and washing are carried out countercurrent in ascending vertical flows of a solution of hydrochloric acid and water when applying reciprocating oscillations, p In this case, after leaching, the sludge is unloaded and fed to the washing using a hydrotransport system. 2. The method according to claim 1, characterized in that the reciprocating vibrations are conducted at an intensity of 800-1000 mm / min. 3. The method according to claim 2, characterized in that water is used in the hydrotransport system when applying sediment for washing. 4. The method according to claim 3, characterized in that when the sludge is unloaded after leaching, an equal amount of sludge is discharged, the volume of water is directed into circulation for mixing with the source water used for the hydrotransport system.