Method of manufacturing high-strength ceramic granules

FIELD: ceramics.

SUBSTANCE: invention relates to manufacture of molded ceramic materials for use as propping agent in production of liquid and gaseous fluids from bored wells. Method comprises briquetting and heat treatment of aluminosilicates kaolin at 1150-1250оС. Resulting mix is ground to average grain size 3-5 μm and loaded into granulator. Before granulation, 1.2-3.0% mineralizer and 5-10% plasticizer are added. Mix is moistened with dozed amount of organic binder and stirred to form granules. At the end of granulation, fired ground material for powdering granules is added in amount 1.2-3.0%. Granules are dried and screened to isolate desired fraction, which is subjected to final firing at 1370-1450оС for 30-60 min and then re-screened into commercial fractions.

EFFECT: enabled manufacture of granules having low loose density and high strength allowing their use at depths up to 14000 feet (4200 m).

3 cl, 1 dwg, 1 tbl, 3 ex

 

The invention relates to the production of molded ceramic material based on aluminum oxide, which can be used in the extraction liquid and flowing gaseous media from the wells as a proppant.

A method of producing a high-strength spherical ceramic grains of calcined raw material (RF patent 2203248, MPK-7: 04 35/64 In, publ. 27.04.2003), including okomkovanie original aluminosilicate raw material, its heat treatment at a temperature 1025-1145° and grinding to the bulk density is 0.45-0.85 grams/cm3and with a mass fraction of particles less than 2 μm - 20%, less than 5 μm - 45%, less than 10 μm - 60%, less than 50 microns and 85%, dosing and loading plate granulator mixture with the addition of 2-5% of the mineralizer dispersion of 10 mm the following chemical composition: Tio; in the form of rutile - 31%, FeO - 27%, SiO2- 13%, MnO - 3,8%, CR2O3- 1,7%, MgO - 1,1%, moistening the crushed material, granulating the descent of the feed granulator additional quantity of the crushed material, dried to a relative humidity of 2-3%, the powder burned material, a preliminary screening of the obtained granules for targeted faction, firing the granules at a temperature of 1350-1450° in a rotating gas furnace, cooling and sieving the granules trademark faction.

The known method has to follow what their weaknesses

1. Thermal treatment of raw materials in the temperature range 1025-1145° does not provide education in the decomposition of kaolinite sufficient amount of crystals of mullite, corresponding to the formula:

3l2About3+6SiO23l2About3×2SiO2+4SiO2

mullite (60%) + cristobalite (40%)

(P.P. Budnikov and other "Technology of ceramics and refractories), State publishing house of literature on construction and building materials, 1962, S. 594).

2. After heat treatment at 1025-1145° and further grinding with a mass fraction of particles less than 2 μm - 20%, less than 5 μm - 45%, less than 10 μm - 60%, less than 50 microns and 85% of the ductility of the material is quite low (the number of plasticity 6,8), therefore, after granulating material with the use of 0.05 to 0.4%aqueous solution of polyvinyl alcohol and further drying to a relative humidity of 2-3% of the compressive strength is also quite small and is 4.2 kg/cm2.

As the strength of the granules in the dry state is quite low, in production, this leads to mechanical failure of dry granules and, accordingly, reduce productivity, and reduce the sphericity and roundness of the granules in accordance with the table of Krumbein and Sloss (GOST R 51761-2001 “aluminosilicate Proppants and API RP60 “Methodological R. the recommendations for testing high strength proppants fillers for hydraulic fracturing”).

To achieve the specified strength of ceramic pellets after firing (i.e. for the formation of a sufficient proportion of the mullite) even when using the specified mineralizer requires increasing firing temperature or ensuring the continuance of finding the material in the zone of action of the firing temperature of from 2 to 6 hours, depending on the grain composition of the charge, which leads to significant energy consumption.

When firing the granules at the specified temperatures of 1350-1450°C in a rotating gas furnace is okomkovanie material under the action of the firing temperature or the so-called education "class", i.e. low-melting eutectic on the surface of the granules when the temperature goes into the liquid phase and correspondingly the adhesion of the granules, resulting in a significant loss of material, and also leads to changes in modes of firing, namely to decrease the firing temperature, which leads to reduction in strength of the ceramic granules.

The technical object of the present invention is to develop a method of producing lightweight, high-strength ceramic granules, which allows to obtain granules with a low bulk density, high strength, allowing the use of these granules at depths to 14,000 feet (4200 meters), sphericity and roundness of 0.9, solubility in acids not bol is e 3%.

The task is achieved by the fact that in the method of manufacturing lightweight, high-strength ceramic granules, including thermal processing of the original aluminosilicate raw material, which is used as kaolin, grinding, introduction pre-processing stage of the mineralizer and plasticizer, granulation in an intensive mixer crushed material under stirring and moisturizing organic binder, adding to the mixture an additional ground calcined material for dusting, drying, pre-sieving to isolate a target fraction, the final firing and sieving the calcined granules according to the invention, heat treatment of the feedstock is carried out at a temperature of 1150-1250° With, the grinding is carried out until the average particle size 3-5 μm, before pelleting as mineralizer enter MgO in an amount of 1.2 to 3.0% relative to the weight of the mixture and the plasticizer in the amount of 5-10% relative to the weight of the mixture, moistening provide metered addition of 0.2-0.4%aqueous solution of organic binder in the amount of 16-20% relative to the weight of the mixture, the mixture is stirred until the formation of granules with a size of 0.2-1.0 mm, at the end of the process of granulation enter substandard sintered powdered material in the amount of 5-10% relative to the weight of the mixture, with a particle size of 3-5 microns, doused to the size of the and granules of 0.5 2 mm, drying the obtained granules is carried out until a residual moisture content of not more than 1.5%, the final firing are within 30-60 minutes

As the plasticizer is injected feedstock. As the organic binder is injected carboxymethylcellulose.

The temperature of 1150-1250° at which carry out heat treatment of the feedstock is optimal and sufficient for the decomposition of kaolinite formed a sufficient amount of mullite in which the strength of the finished granules maximum.

The implementation of grinding to an average particle size of 3-5 microns with a given distribution of dispersion provides the tightest possible packing of particles by granulation, which consequently increases the strength of the ceramic granules and increased sphericity and roundness of granules.

Introduction before pelleting as mineralizer MgO in an amount of 1.2 to 3.0% relative to the weight of the mixture is sufficient to intensify the process of mineral formation and reduce the time of the final annealing. Accelerating effect of mineralizer is explained by the formation of low-melting mixtures of one or more components of the mixture; the surface area of interaction between the reactants increases, and increases the rate of diffusion. On the other hand, the mechanism of action of mineralizers on the acceleration process is and can be explained by the removal of the lattice of a solid body of individual atoms and molecules, cause molecular porous bodies, forming pseudomorphs after the original crystals. The advent of molecular-porous colloidal porous bodies plays a significant role in the capture of solid impurities and injected into the mixture of additives that significantly affects the communication between components.

Introduction in the mixture of this mineralizer can reduce the residence time of the material under the action of temperature firing 1370-1450° 30-60 minutes without losing the durability of the pellets.

The introduction of the plasticizer in the amount of 5-10% relative to the weight of the mixture can increase the plasticity of the material for granulation by 40-45% and, consequently, the strength of granules to compression after granulation in the mixer "EIRICH and drying to a relative humidity of not more than 1.5% increases by 30-40%.

The amount of aqueous solution of organic binder 16-20% relative to the weight of the mixture with a given concentration of 0.2-0.4% provides uniform wetting of the mixture.

Stirring the mixture to form granules with a size of 0.2-1.0 mm allows to obtain the optimal size of the granules to form the basis for the finished granules and are an indication to perform a dusting.

Add at the end of the process of granulation of burnt ground material in the amount of 5-10% relative to the weight of the mixture is subject to the full-time, to make dusting granules, and a particle size of 3-5 μm is optimal for the formation of granules of high sphericity and roundness, while on the surface of the granules formed layer of material with a high content of mullite (55-60%). On the surface of the granules after dusting sintered powdered material layer is formed of a material with a high melting temperature (1850±20° and when the firing temperature 1370-1450°C it does not form the melt on the surface of the granules, the granules do not stick together in the furnace (i.e. not formed "class").

Implementation drying the obtained granules to a residual moisture content not exceeding 1,5%provides optimal moisture and prevents dryness of the granules and their destruction in the dry state.

The final firing within 30-60 minutes intensifies the burning process, which significantly reduces energy consumption.

Used as the mineralizer MgO, as can be seen from the graph (Figure 1), gives the greatest effect acceleration of mullitization process.

Use as a plasticizer of raw materials economically.

Used as organic binder is carboxymethylcellulose provides reliable hydration mix, economically and technologically.

The method consists in the following.

Raw materials - silica-kaolin bitteroot, thermally process pritemperature 1150-1250° C. the resulting mixture is ground to an average size of 3-5 microns, is fed into the granulator. Before pelleting administered 1,2-3,0% of the mineralizer and 5-10% of plasticizer in the form of raw materials. The mixture is moistened dosed amount of organic binder are mixed to form granules, at the end of the granulation process add 5-10% burnt ground material for dusting granules. The obtained granules are dried, pre scatter for targeted faction, conduct a final calcination at a temperature of 1370-1450°C for 30-60 min and sieving the granules trademark faction.

The method is illustrated by the table with the comparative strength and ductility of the granules at the introduction of this plasticizer; figure 1 - graph of the amount of the formed mullite depending on the firing temperature.

The method is as follows.

Take the original aluminosilicate raw materials (kaolin) with the content of Al2About3- 35-45% and SiO2- 40-50% and bitteroot.

Example 1.

Produce heat source aluminosilicate raw materials at a temperature of 1150° C.

Such temperature for heat treatment is insufficient to decomposition of kaolinite formed a sufficient amount of mullite, which ensures high durability of the finished granules. The settlement of the e heat treatment of the resulting material is subjected to grinding to an average particle size of 3 μm, and fed into the granulator - intensive countercurrent mixer company "EIRICH".

The particle size is too small, therefore decreases the sphericity of the pellets by granulation, and also increase the energy consumption for grinding.

Before granulation in the crushed raw material is introduced to 1.2% of mineralizer - MgO and 5% of plasticizer in the form of raw materials.

This amount of mineralizer is not enough intensifies the process of alltournative, as well as a small amount of mineralizer is quite difficult to evenly mixed throughout the mass of the mixture.

The specified amount of the plasticizer is not enough to ensure the plasticity of the mixture for granulation.

Mix the dry mixture and to hydrate dosed enter 16% relative to the mixture of 0.2%aqueous solution of carboxymethylcellulose.

The amount and concentration of carboxymethyl cellulose is not sufficient for uniform wetting of the mixture.

In the granulator at the end of the granulation process add 5% crushed to particle size of 3 μm burned material for dusting.

This amount of burnt material is not sufficient for dusting granules in order to ensure the roundness of the pellets and avoid the sticking of the pellets in the pellet mill, the particle size is too small, which degrades the quality of pellets, leads to additional energy consumption during grinding.

Granules OK the population to an average size of 0.5 mm, dried to a relative humidity of 1%. The granule size is too small and results in a significant decrease in the number of manufactured products, and given the size of the granules does not cover the whole range of product fractions. This moisture is insufficient, because the dryness of the granules and, as a consequence, their destruction in the dry state.

The final firing is conducted at a temperature of 1370° C for 30 minutes At this temperature for firing the granules do not have sufficient strength, there is not enough time for sintering the granules and ensure their durability.

Example 2.

Produce heat source aluminosilicate raw materials at 1200°C. This heat treatment temperature optimum for decomposition of kaolinite formed a sufficient amount of mullite in which the strength of the finished granules maximum.

After the heat treatment, the resulting material is subjected to grinding to an average particle size of 4 μm, and fed into the granulator - intensive countercurrent mixer company "EIRICH".

The particle size sufficient to provide the tightest possible packing of particles by granulation, which consequently increases the strength of the ceramic granules, as well as to increase their sphericity and roundness.

Before granulation in the crushed raw material is introduced to 2.1% of the mineralizer is - MgO and 7.5% of the plasticizer in the form of raw materials (kaolin).

This amount of mineralizer enough in order to intensify the process of mineral formation and education necessary amount of mullite.

This amount of mineralizer can reduce the heat treatment time up to 45 min at a temperature firing 1370-1450° With no loss of strength of the granules.

A specified amount of plasticizer, i.e. 7.5 percent, sufficient to provide the plasticity of the mixture for granulation and, consequently, the strength of granules to compression after pelleting increases, and there is no mechanical destruction of the granules in the dry state and as a consequence remain high sphericity and roundness of granules.

Mix the dry mixture and to hydrate dosed enter 18% relative to the mixture of a 0.3%aqueous solution of carboxymethylcellulose.

The amount and concentration of carboxymethyl cellulose is sufficient for uniform wetting of the mixture.

In the granulator before the end of the granulation process add 7.5% of the calcined material crushed to an average particle size of 4 μm for dusting.

This amount of burnt material for dusting with a specified particle size sufficient for dusting granules and provides for granulation formation greatest number of target fracc and, on the surface of the granules formed a necessary layer of material with a high content of mullite, and achieve high performance in their sphericity and roundness.

Granules doused to medium size 1.25 mm, dried to a relative humidity of 1.25%. The granule size sufficient to provide a full range of commodity fractions. The optimal humidity, to prevent overdrying of the material and, as a consequence, the mechanical destruction of dry granules, and also to eliminate downtime due to stuck nedosushennye material.

The final firing is carried out at a temperature of 1400° C for 45 min, which provides the highest durability of ceramic granules.

Example 3.

Produce heat source aluminosilicate raw materials at a temperature of 1250° C.

This heat treatment temperature leads to additional costs as at carrying out heat treatment, and grinding the material after heat treatment. The quality of the granules thus not improving.

After the heat treatment, the resulting material is subjected to grinding to an average particle size of 5 μm, and fed into the granulator - intensive countercurrent mixer company "EIRICH".

Grinding with a given distribution of dispersion does not provide the tightest possible packing of particles by granulation, which consequently reduces the strength of eroticheskih granules, and also reduces the sphericity and roundness of granules.

Before granulation in the crushed raw material is introduced to 3.0% of mineralizer - MgO and 10.0% of the plasticizer in the form of raw materials (kaolin).

This amount of mineralizer bring additional costs without significant further intensifitsirovany process of mineral formation.

The introduction of a quantity of the plasticizer, i.e. 10,0%, leads to an increase in cost and decrease the strength of the ceramic granules, which is explained by the formation of internal defects during drying of the granules.

Mix the dry mixture and to hydrate dosed impose 20% relative to the mixture of 0.4%aqueous solution of carboxymethylcellulose.

The amount and concentration of carboxymethylcellulose overly pereubejdat mixture, which leads to deterioration of the quality of the mixture, more time is required for drying, which increases the energy consumption.

In the granulator add 10,0% calcined material crushed to an average particle size of 5 μm for dusting granules.

This amount of burnt material for dusting is unnecessary, as it leads to additional costs, as well as by granulation unused material powder remain in the form of dust, which leads to a significant reduction in the number of target fractions. The powder is a material, crushed to an average particle size of 5 μm, affects the sphericity and roundness of the granules, and the granules have a rough surface.

Granules doused to an average size of 2.0 mm, dried to a relative humidity of 1.5%. The size of the granules does not provide the full range of product fractions, i.e. reduces the number of target fractions. The humidity increased, hence, the deterioration of the preliminary screening for the selection of the target groups as well as experiencing downtime due to sticking of the wet material.

The final firing is carried out at a temperature of 1450°C for 60 minutes the firing temperature and the firing time lead to the formation of "class" in the furnace, as well as to additional energy consumption.

Thus, the inventive method of obtaining lightweight, high-strength ceramic granules allows to obtain granules with a bulk density 5-1,65 g/cm3high strength (not more than 5% of the destroyed pellet fraction 20/40 at a pressure of 70 MPa), allowing the use of these granules at depths to 14,000 feet (4200 meters), sphericity and roundness 0.9, solubility in acids of not more than 3%. The inventive method is economical and productive.

1. Method for the production of lightweight, high-strength ceramic granules, including thermal treatment the original aluminosilicate raw materials, which is used as kaolin, grinding, introduction pre-processing stage of the mineralizer and plasticizer, granulation in an intensive mixer crushed material under stirring and moisturizing organic binder, drying, pre-sieving to isolate a target fraction, the final firing and sieving the calcined granules, characterized in that the heat treatment of the feedstock is carried out at a temperature of 1150-1250°C, the grinding is carried out until the particle size of 3-5 microns, before pelleting as mineralizer enter MgO in an amount of 1.2 to 3.0% relative to the weight of the mixture, and the plasticizer in the amount of 5-10% relative to the weight of the mixture, moistening exercise metered addition of 0.2-0.4%aqueous solution of organic binder in the amount of 16-20% relative to the weight of the mixture, the mixture is stirred until the formation of granules with a size of 0.2-1.0 mm, at the end of the process of granulation enter sintered powdered material in the amount of 5-10% relative to the weight of the mixture, with a particle size of 3-5 microns, doused with up to granule size 0.5-2 mm, drying the obtained granules is carried out until a residual moisture content of not more than 1.5%, the final firing are within 30-60 minutes

2. The method according to claim 1, characterized in that the plasticizer is injected feedstock kaolin.

3. The method according to claim 1, characterized in that the organic with sousage enter carboxymethylcellulose.



 

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