RU2619622C1 - Method of fine clay material producing - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to minerals processing and can be used to produce highly pure and/or modified clays, drilling muds preparation. Method of fine clay material producing involves breaking of initial clayey or clay-containing material in fluid until obtaining suspension, followed by extraction and removal of sediment from suspension, including fragmental product, and obtaining suspension containing fine fraction of clayey material, concentration of obtained suspension, wherein, during breaking mixture of liquid and initial material repeatedly passed through ejector providing supersonic flow and braking of suspension with formation of shock waves in ejector and three-phase mixture at ejector outlet, containing liquid, initial material and gas, wherein ejector is used with flow section, which minimum size is not less than for 3 times exceeds introduced clayey or clay-containing material particles size, and which amount in suspension is 2–15 wt%.

EFFECT: technical result consists in maximum removal of fragmental product from clayey minerals.

9 cl, 6 dwg, 1 tbl

Description

Technical field

The invention relates to mineral processing and can be used to produce highly pure and / or modified clays, and to prepare drilling fluids. The method is implemented by exfoliating ("exfoliating") clay minerals to submicron sizes and releasing clastic (solid) minerals by known methods, for example, in centrifuges, hydrocyclones or sedimentation.

State of the art

A known method of producing clay suspensions, in which the raw material is washed out with exfoliation of clay material and the release of clastic material in native form (for example, in scrubber-butyres, see "Mountain Encyclopedia"). The disadvantage of this method is the impossibility of obtaining pure clay suspensions, since the size of the removed clutter is determined by the size of the holes of the sieves installed in the device. As a rule, a clay suspension (at normal pressure and, for example, a concentration of only 6% by weight. Ceases to pass through a sieve with a mesh size of 150 microns). In addition, a significant disadvantage is the low speed of the exfoliation process.

Closest to the invention is a method for producing a finely dispersed clay material, mainly kaolin, comprising dissolving the starting material in water to obtain a suspension with a moisture content of 92%, hydrocyclone enrichment with the release of sediment and discharge containing a finely divided fraction of the material, followed by thickening and dehydration of the discharge, while the precipitate isolated after hydrocyclone enrichment is crushed, and then it is introduced during dissolution of the starting material, maintaining the moisture content of the suspension equal to 92% by water additions (RF patent No. 2034811).

The disadvantage of this method is the constant increase in the amount of clastic material in the suspension released from clay raw materials, which, ultimately, will lead to complete displacement of clay minerals in the suspension by clastic. In addition, in this way it is impossible to isolate grains of a clad material of micron and submicron sizes, especially from clay suspensions containing montmorillonite (or other swellable minerals), since nanosized clay particles impede sedimentation of clastic material in a suspension with humidity up to 98%. Moreover, with an increase in the amount of clastic material, not only clay minerals will exfoliate, but also mechanical destruction of clastic (especially soft, for example, iron oxide) minerals will occur, which will lead to secondary pollution of clays.

Disclosure of invention

The objective of the invention is to obtain highly pure clays with a minimum content of clastic minerals.

EFFECT: maximum removal of clastic material from clay minerals. The implementation of the proposed method allows to obtain clay material with a content of clastic minerals up to 2% weight.

This task and the technical result are achieved in that a method for producing a finely dispersed clay material includes dissolving the initial clay or clay-containing material in a liquid to obtain a suspension, followed by isolation and removal from the suspension of a precipitate comprising a clastic material, and obtaining a suspension containing a finely divided fraction of clay material, concentration the resulting suspension, while in the process of dissolution, the mixture of liquid and the source material is repeatedly passed through the ejection OR, providing supersonic flow and braking of the suspension with the formation of shock waves in the ejector and a three-phase mixture at the outlet of the ejector containing liquid, source material and gas, while the ejector is used with a cross section, the minimum size of which is at least 3 times the size of the particles introduced clay or clay-containing material, the amount of which in suspension is 2-15% by weight.

Before feeding into the ejector, preliminary mixing of clay material and liquid is carried out.

In addition, the precipitate is extracted and removed when the desired clay particle size is achieved, while a suspension containing a fine fraction of clay minerals is additionally passed through a second supersonic ejector with a lower minimum cross section compared to the first ejector by 20%.

Preferably, the dissolution of the source material to accelerate the process of exfoliation of the clay material is carried out in a liquid in the presence of a polyelectrolyte.

Preferably, liquid glass is used as the polyelectrolyte.

Preferably, after removing the precipitate, a suspension containing a fine fraction of clay minerals is left to stand for 1-72 hours, followed by separation of the precipitate formed.

Preferably, when using the clay material in calcium form, the liquid glass is taken in an amount that allows the clay minerals to be converted from the calcium form to the sodium form.

Preferably, deionized or natural water or polyelectrolyte solutions are used as the liquid.

It should be noted that the use of polyelectrolytes in the liquid for dissolution of the initial clay or clay-containing material allows accelerating the exfoliation of clay minerals and their "separation" from clastic minerals. In addition, the use of sodium polyelectrolytes allows the replacement of calcium in the composition of clay minerals with sodium.

It is preferable that a solution of soda, a solution of sodium tripolyphosphate, barium sulfate is used as a solution of polyelectrolytes.

Raw materials (clay, clay powders or clay-containing material, for example tripoli, diatomite, etc.), in addition to plastic (clay) minerals, contain a clastic (granular) component consisting of harder minerals such as limestone, quartz, feldspars, etc. ., which are among clay minerals and make up from 2-5 to 40% by weight. Moreover, these minerals are also extremely heterogeneous in strength, both in nature and due to their different interactions with the liquids in which they are dispersed.

The size of the clastic debris varies in a wide range: from submicron to tens of millimeters, determined by the nature of the feedstock and its processing technology. The greatest difficulty for separation is caused by micron and submicron particles. In addition, in the feedstock, both in clay minerals and in clastic minerals, there are cavities and cracks filled with air or gases that interfere with the interaction of liquid and solid (wetting them with liquid), and even add “buoyancy” to the clastic material. In existing technological schemes, this is solved by the use of high-energy dispersants or colloid mills, which, in addition to significant energy costs and low reliability, also have a significant drawback: they modify and disperse also the clastic material, causing secondary pollution of precisely those clay mineral fractions that are in demand. Their subsequent isolation is very difficult, and often impossible. Studies of various materials showed that clays and clay powders of the most famous brands contain at least 2-5% of the clastic material. The claimed invention allows to obtain clay and clay powders with a content of clastic material of less than 2%.

The claimed invention is based on the use of ejectors that implement supersonic flow and braking of the suspension with the formation of shock waves in the ejector and a three-phase mixture at the outlet of the ejector containing liquid, source material and gas. In well-known ejectors that implement a supersonic flow of a liquid, its sharp braking, obtaining a two-phase (gas-liquid) mixture is described. Moreover, the presence of a clastic (solid) material (which is the third component of the system) in the suspension was not taken into account. The natural properties of the clastic material were also not taken into account. The properties of a three-phase mixture (liquid, clastic (solid material), gas (air) are different from the properties of a two-phase mixture. When the stream is repeatedly passed through a supersonic ejector, clay minerals are separated from the grains of other minerals, because liquid (water), first of all, the agglomerates of clay minerals are destroyed gradually, which is apparently due to the kinetics of surface hydration and the subsequent separation of the hydrated layer, and since all ejectors that realize the supersonic flow of the mixture have varying (variable) cross-sections for flow, the maximum size of the solid phase material should not exceed 1/3 of the minimum cross-section of the ejector to prevent clogging of holes. It has been experimentally established that the most effective suspension (in the water-clay-air system) occurs when the quantity clay in the mixture 2-15% by weight More than 15% of the swollen clay cause clogging of the ejector due to the increased viscosity of the suspension or require significant energy costs.

At a certain stage in the operation of the ejector (after multiple passing of the mixture) and removal of the clastic material, it is advisable to send the clay slurry to a similar (second) ejector with a smaller minimum cross section, since it seems that the degree (force) of the effect on the particles in suspension depends on the size of cavitation bubbles and, as a result, the ultrasonic effect, which allows one to obtain finer fractions.

The introduction of a mixture of polyelectrolytes allows you to disrupt the double electric layer formed around solid particles, which positively affects the speed of obtaining a suspension and obtaining smaller sizes of clay particles in suspension.

The use of water glass as an additive leads to both the acceleration of the exfoliation process and the replacement of calcium (magnesium) in clays by sodium (in calcium-containing clays), which positively affects the properties of clay (for example, cation exchange capacity). The amount of water glass is determined by the type of clay material, preferably in a concentration of up to 1% by weight.

Settling the suspension obtained for 1-72 hours, especially after the introduction of polyelectrolytes, in particular liquid glass, leads to the formation of a dense precipitate. At the same time, a clay suspension is formed in the upper part that does not contain clastic material, which was confirmed by the results of x-ray phase analysis (XRD).

The present invention is aimed at the most complete removal of clastic material, while combining the process of "washing" grains of non-clay minerals and exfoliation of clay minerals, followed by separation by known methods, for example on hydrocyclones, which allows to obtain refined clay. When the method is implemented, the suspension of clay minerals does not become contaminated with fragments of secondary crushing of non-clay minerals. In addition, it is possible to modify (transfer) clay minerals from the calcium (and / or magnesium) form to the sodium form. The inventive method allows to obtain clay material with particle sizes from 40 nm to 1 μm.

Brief Description of the Drawings

The invention is illustrated by drawings.

In FIG. 1 is a schematic diagram of a clay cleaning stand, where 1 is a container equipped with a stirrer, 2 is a pump, 3 is a pressure gauge, 4 is a filter, 5 is a device that implements the effect of the formation of a two-phase supersonic mixture and the effect of compaction shocks on it, for example, a supersonic ejector, 6 - a vacuum gauge, 7, 8 - a device for separating sediment and discharge, for example a hydrocyclone or centrifuge, 9, 10 - tanks for coarse sediment.

In FIG. 2 is a graph illustrating a decrease in particle size depending on the processing ratio of the suspension.

In FIG. Figure 3 shows the diffraction pattern of a suspension of bentonite-palygorskite mineral raw materials from the Borschevsky deposit, after separation of the clastic phase on a hydrocyclone.

In FIG. Figure 4 shows the diffraction pattern of a suspension of bentonite-palygorskite mineral raw materials from the Borschevsky deposit, after separation of the clastic phase on a hydrocyclone, treatment with liquid glass and settling for 1.5 hours, followed by separation of the liquid from the precipitate.

In FIG. Figure 5 shows the diffraction pattern of the dense sediment of the Borschevskoye field, after separation of the clastic phase on a hydrocyclone, treatment with liquid glass and settling for 1.5 hours.

In FIG. 6 is a photograph of an apparatus for implementing the method, where 1 is a container, 2 is a pump, 5 is an ejector, 7, 8 are hydrocyclones.

The implementation of the invention

The proposed method is implemented as follows (Fig. 1).

In a container equipped with a stirrer (1), the calculated amount of liquid and clay enters with stirring. The particle size of the clay or clay-containing starting material does not exceed 1/3 of the minimum passage of the ejector (5), which implements the effect of the formation of a three-phase mixture containing liquid, source material and gas (air), with a supersonic flow of the mixture and its inhibition with the formation of pressure surges. The particle size of the clay and grains of the clastic material associated with it is determined by the minimum flow area of the device to prevent clogging, which ultimately leads to an increase in the reliability of its operation. Both deionized water and natural water, solutions of polyelectrolytes (for example, soda solutions, sodium tripolyphosphate solution, etc.), etc. can be used as liquids. The starting material can be represented by natural clay with initial moisture, specially prepared clay powders, clay-containing rocks, for example, tripoli, diatomites, moraine deposits, etc. In addition, a pre-dissolved mixture of clay and liquid in scrubber buters or clay mixers can enter the tank. From the container (1), the clay and liquid mixture is pumped (2) to the ejector (5), which implements the effect of the formation of a three-phase supersonic mixture with the effect of compaction surges. When passing through the ejector, the mixture undergoes sharp pressure drops, sharp changes in the velocity of the gas phase in magnitude and direction, which leads to crushing of liquid droplets, a change in their configuration and, as a result, maximum contact of clay particles with the liquid. Clay particles detach from the clastic material due to their different nature, i.e. grains of clastic material are centers of destruction of clay-granular aggregates. In this case, the liquid effectively penetrates into the interplanar space between packets in clay aggregates. In addition, during collisions with each other, the destruction of clay aggregates also occurs. Studies have shown that the rate of clay destruction depends on the pressure at the inlet of the ejector (set by pump 2 and recorded by a pressure gauge 3) and its differential at the outlet, temperature of the mixture, ratio W: T of the mixture, and also on the multiplicity of suspension passing through the device, t .e. repeated exposure to shock waves, as well as from the type of rock-forming clay mineral. Filter 4 (mechanical) is designed to guarantee the prevention of clogging of the ejector holes. The amount of sucked air into the ejector 5 is controlled by a vacuum gauge 6.

To realize the multiplicity effect, the suspension from the device (5) is again fed into the container (1), and upon reaching the specified size of clay particles it is directed to the device (7, 8), which provides the precipitate from the suspension (by obtaining a suspension containing fine clay material), for example on a hydrocyclone or centrifuge. In this case, a clastic material with a particle size greater than a given or having a higher density is separated in a container 9, 10.

Repeatedly passing a mixture of a liquid and a source material (clay of the Borschevsky field) through an ejector leads to an increase in the number of fine fractions of clay particles, as shown in FIG. 2.

After removal of the clastic material in containers 9, 10, the suspension can be sent to a device similar to (5), but having a smaller minimum cross-section, which under similar (technical and technological) conditions will allow a more intensive effect on the suspension, i.e. to obtain clay particles with a smaller size. For example, when using an ejector (with a productivity of 5 cubic m / h) with a minimum flow cross section of 1.2 mm, the required viscosity of a suspension prepared from clay powder and water was achieved in 3 minutes of processing, and when using two ejectors (productivity of each 2.5 cubic meters m / h) with a minimum bore of 0.8 mm - less than 2 minutes.

The addition of a polyelectrolyte to the liquid significantly accelerates the crushing of clay particles (Table 1).

The use of liquid glass as a polyelectrolyte leads to the formation of a dense precipitate, with which all clastic impurities sediment, with the result that only pure clay minerals remain in the suspension. The liquid phase obtained after introducing liquid glass into the suspension and removing the clastic material on known devices (hydrocyclone or centrifuge) is left to stand for 1-72 hours, followed by separation of the liquid from the precipitate. At the same time, there is no clastic material in the liquid phase, which is confirmed by the XRD data (X-ray phase analysis) (Fig. 3-5).

In addition, the use of liquid glass as a polyelectrolyte makes it possible to transfer clay minerals from a calcium form to a sodium form (Fig. 4). For this, liquid glass is taken in the amount necessary to replace calcium ions in clay minerals with Na ions. The amount of liquid glass is selected depending on the composition of the feedstock empirically. The sample in the presented diffractogram was obtained by adding 10 grams per 900 grams of the original clays of the Borschevsky field.

An example implementation of the method.

The method was carried out on the installation created by the inventors (Fig. 6).

As the device that implements the effect of the formation of a two-phase supersonic mixture and the effect of shock waves on it, an ejector made according to patent No. 2209350 was chosen.

The ejector contained a receiving chamber with a gas supply pipe and a fluid supply pipe mounted on the chamber axis with a multi-nozzle nozzle at the outlet, a confuser, a mixing chamber and a diffuser, the multi-nozzle nozzle being installed so that the nozzles were evenly distributed over the nozzle area corresponding to the cross-sectional projection of the mixing chamber the ratio of the cross-sectional area of the mixing chamber and the sum of the areas of the nozzle holes is 4: 1, the distance between the nozzle and the mixing chamber is 1.5 diameters mixing chambers. The opening angle of the confuser was 120 degrees. 18 nozzles were used in the nozzle, and each nozzle had the shape of a truncated cone with a half-opening angle of 45 degrees passing into the cylinder, while the length of the cylindrical part of the nozzle was 1.0 of its diameter. The diffuser was made expandable (with a half-opening angle of 6 degrees) along the flow direction, while the area of its output section was 4 of the cross-sectional area of the mixing chamber.

The method of operation of the ejector includes the supply of liquid under pressure to the nozzle nozzle, the non-pressure supply of the gaseous medium to the ejector nozzle, mixing in the chamber for mixing the liquid (suspension) with the gaseous medium to form an equilibrium mixture, and the mixture is discharged through the diffuser, the liquid being supplied under pressure providing a speed its supply, exceeding the speed of sound in the resulting mixture by at least 25%, while maintaining the mass ratio of the flow rate of the gas medium to liquid (ejection coefficient) of not more than 0.01.

When the ejector is operating in the shock waves, there is a sharp change in the velocity of the gas phase in magnitude and direction, as well as a sharp change in pressure, which leads to crushing of the droplets of the suspension and a change in their shape. The liquid – gas contact surface increases by a factor of a thousand, which ensures guaranteed mixing of the components of the liquid and gaseous media at the submicron level.

A hydrocyclone with a diameter of 50 mm and a sand nozzle with a diameter of 4 mm was used as a device for obtaining a suspension with a finely dispersed clay material. A centrifugal pump was also used in the installation, which ensured that the pressure at the inlet to the ejector was reached from 2.5 to 6 atm. Natural clay of the Borschevskoye field was used as a feedstock. Studies were conducted on 6% (by weight) of a mixture of clay with water. The initial size of the clay did not exceed 250 microns (the clay was pre-elutriated and passed through a sieve), because the diameter of the minimum passage of the ejector was 0.8 mm. The volume of intake air was up to 3 volumes of the volume of the pumped suspension.

All work on the installation (Fig. 6) was carried out according to the standard method: Natural clays of the Borschevsky field weighing 1.1 kg were manually elutriated in 15 liters of tap water on sieves up to - 200 microns, because the minimum passage opening of the applied ejector is 800 μm; the isolated clastic material was weighed. The weight of the selected coarse clastic material ranged from 150 to 200 grams. In further works, this material was not used. The work was carried out indoors at normal pressure and room temperature. The subsurface material was poured into the tank 1. After turning on the pump 2, the material passed through the ejector 3 and returned back to the tank 1. The pump was turned on for 1 to 3 minutes. After that, the suspension was supplied to one of the hydrocyclones 4, where the separation of the clastic material into the tank (buckets are conventionally shown).

When using a polyelectrolyte (standard sodium liquid glass was used during operation) in an amount of 10 grams per experiment, it was introduced by pouring it into a suspension before turning on the pump.

Samples were taken for analysis from tank 1 to control the quality of the finely dispersed clay material (composition and particle size in suspension), the particle size was less than 1 μm.

Thus, the claimed method was obtained high-purity clay material with a content of clastic material of less than 1.5% by weight.

The proposed invention can be implemented to obtain very pure (without clastic material) clays, as well as to obtain modified clays.

In addition, when applying the invention, it is possible to obtain clays from unconventional sources: tripoli, diatomites, moraine deposits (containing up to 20% clays of various compositions), in the development of which no clay component is currently released at all, which affects the quality of the main useful component (for example, diatomite).

Claims (9)

1. A method of producing a finely dispersed clay material, comprising dissolving the original clay or clay-containing material in a liquid to obtain a suspension, followed by isolation and removal from the suspension of a precipitate comprising a clastic material, and obtaining a suspension containing a finely divided fraction of clay material, concentrating the resulting suspension, characterized in that in the process of dissolution, the mixture of liquid and the starting material is repeatedly passed through an ejector, which provides a supersonic flow, etc. braking the suspension with the formation of shock waves in the ejector and a three-phase mixture at the outlet of the ejector containing liquid, source material and gas, the ejector being used with a cross section, the minimum size of which is at least 3 times the particle size of the clay or clay-containing material introduced, and the amount of which is 2-15% by weight. in suspension. 2. The method according to p. 1, characterized in that before feeding into the ejector carry out preliminary mixing of clay material and liquid. 3. The method according to p. 1, characterized in that the selection and removal of sediment is carried out upon reaching the desired size of clay particles, while the suspension containing a finely dispersed fraction of clay minerals is additionally passed through a second supersonic ejector with a lower minimum cross section compared to the first ejector by 20%. 4. The method according to p. 1, characterized in that after removal of the precipitate, a suspension containing a finely divided fraction of clay minerals is settled for 1-72 hours, followed by separation of the precipitate formed. 5. The method according to p. 1, characterized in that the dissolution of the source material to accelerate the process of exfoliation of the clay material is carried out in a liquid in the presence of a polyelectrolyte. 6. The method according to p. 5, characterized in that the liquid glass is used as the polyelectrolyte. 7. The method according to p. 6, characterized in that when using clay material in calcium form, the liquid glass is taken in an amount that allows you to convert clay minerals from calcium form to sodium form. 8. The method according to p. 5, characterized in that as the polyelectrolytes use a solution of soda, a solution of sodium tripolyphosphate, barium sulfate. 9. The method according to p. 1, characterized in that the liquid used is deionized or natural water.

Images