RU2290382C1 - Method of production of the refractory high-strength spherical granules (propants) - Google Patents

Abstract

FIELD: construction materials industry; oil-producing industry; construction materials industry; production of the molding ceramic materials.

SUBSTANCE: the invention is pertaining to production of the molding ceramic materials, in particular, to production of the refractory high-strength spherical granules (propants), which may be used at extraction of the liquid and leaky gaseous mediums from the drill holes as the propping agent. The technical result of the invention is reduction of the cost of the products, decreased power input at production, the increased strength of the finished products. The method includes calcination of the aluminum silicate raw, grinding at the centrifugal mill with the air separator, granulation with the batching addition of the moisture, dusting, granules balling, drying in two stages: drying in the UHF field up to the residual humidity of 10 % and drying by convection up to residual humidity of 1-3 %, the preliminary sowing, the roasting and the final sowing. At that they use the aluminum silicate raw with the components ratio (in mass. %): Al₂О₃ - 50-60, SiO₂ - 25-35, Fe₂O₃ - 5-15.

EFFECT: the invention ensures reduction of the prime cost of the products, decreased power input at production, the increased strength of the finished products.

3 ex, 1 tbl

Description

The invention relates to the production of molded ceramic materials that can be used in the production of liquid and gaseous fluids from boreholes as a proppant.

A known method of manufacturing refractory high-strength spherical granules (RU p. No. 2229456, IPC S 04 B 35/101, 35/622, from 02.04.02, publ. 27.05.04.).

The specified method is selected by the applicant as the closest analogue (prototype).

The disadvantage of this method is that the initial aluminosilicate raw material contains Al ₂ About ₃ , more than 60%, Fe ₂ About ₃ up to 3% in relation to the mass. Bauxites with such a ratio of components are used by the aluminum industry - their main consumer, which narrows the raw material base and leads to an increase in the cost of raw materials.

The technical objectives of the invention are to reduce the cost of production through the use of cheaper bauxite raw materials, reduce energy consumption in production, increase the strength of the finished product.

The objectives are achieved in that in a method for producing refractory high-strength ceramic granules (proppants), including calcining aluminosilicate raw materials, grinding, granulation with dosed moisture, dusting, pelletizing, drying, preliminary sieving, firing, final sieving, according to the invention as a starting aluminosilicate raw materials are used with the following ratio of components wt.%: Al ₂ O ₃ - 50-60, SiO ₂ - 25-35, Fe ₂ O ₃ - 5-15, grinding of the raw material after calcination is carried out by centrifugal a mill with an air separator, drying of granular raw materials is carried out previously in the field of microwave currents to a relative humidity of 10.0%, and finally - by convection to a relative humidity of 1.0-3.0%.

The use of aluminosilicate raw materials as the starting material with the claimed ratio of components proposed by the applicant, i.e. Al ₂ O ₃ - 50-60%, SiO ₂ - 25-35%, Fe ₂ O ₃ - 5-15%, allows you to expand the raw material base, i.e. use cheaper raw materials, which allows to reduce the cost of finished products.

The grinding of calcined raw materials in a centrifugal mill with an air separator ensures the destruction of particles of the feedstock along the boundaries of the crystals, i.e. on the weak points of the crystal lattice, which reduces the power required for this, i.e. reduce energy costs.

The resulting material is solid crystals, which allows to achieve maximum packing density during granulation, and also to eliminate weaknesses of the crystal lattice during grinding, which, in turn, improves the sintering of the material during firing and increases the mechanical strength of the product.

The drying of granular material in two stages, i.e. previously in the field of microwave currents to a relative humidity of 10% and finally by convection, for example in a drying drum, to a relative humidity of 1.0-3.0%, it can significantly reduce the internal (closed) porosity of the granules and prevent the formation of microcracks in them. In microwave drying, the evaporation of moisture from the surface layer of granules occurs evenly from all layers, as a result of which the internal porosity decreases by an average of 50%, which significantly increases the strength of the granules after the final firing (see table).

When drying in the field of high-frequency currents, the material is placed between two electrodes, to which alternating current of high frequency is supplied through the wires. Under the influence of an electric field, ions and electrons in a material change the direction of motion synchronously with a change in the sign of the charge of the electrodes, dipole molecules acquire a rotational motion, and non-polar molecules polarize as a result of the displacement of their charges. These processes, accompanied by friction, lead to the release of heat. The generated heat heats the material, promoting the movement of moisture to the peripheral layers and its evaporation from the surface of the body.

When drying in a field of high-frequency currents, the material inside has a higher temperature than on the surface; the latter intensifies the drying process, as diffusion and thermal diffusion gradients are directed in one direction.

The use of drying in the field of high-frequency currents ensures uniform heating of the entire volume of granules. The inner layers are heated stronger than the peripheral, because the surface of the granules is cooled as a result of surface evaporation of moisture and heat loss to the environment. As a result, moisture is removed primarily from the inner layers of the granules.

This method (microwave) is quite energy-intensive and it is impractical to dry the material in this way to final humidity, therefore, the combined drying method is used - preliminary drying to a residual moisture content of 10% in the field of microwave currents and then final drying to a relative humidity of 1.0-3.0% convection method due to thermal radiation, that is, in a drying drum.

As a result of the patent research, no similar technical solutions known from the prior art that are characterized by the claimed combination of features have been identified, which allows us to conclude that the proposed invention meets the patentability criteria of “novelty” and “inventive step”, may find application in industry in the production of proppants, etc. e. meets the criterion of "industrial applicability".

The method is illustrated in the table with the main characteristics of the obtained proppants.

The essence of the method is as follows.

Aluminosilicate raw materials with a ratio of components, wt.%: Al ₂ O ₃ - 50-60, SiO ₂ - 25-35, Fe ₂ O ₃ - 5-15, calcined, subjected to grinding in a centrifugal mill with an air separator, dried after granulation in two stages: drying in the field of microwave currents to a residual moisture content of 10% and convection to a residual moisture content of 1-3%.

A method of obtaining refractory high-strength spherical granules (proppants) is as follows.

The initial aluminosilicate raw material in the form of bauxite with a content (wt.%) Al ₂ O ₃ from 50.0% to 60.0%, SiO ₂ from 25.0 to 35.0%, Fe ₂ O ₃ from 5.0% to 15.0% are calcined (calcined) at a temperature of 900-1100 ° C, subjected to grinding in a centrifugal mill to an average particle size of 3-5 microns, granulated using an EIRICH counter-current intensive mixer. Granulation is carried out without the use of binders.

The granulation order is as follows.

Composing the mixture using the EIRICH mixer, loading the crushed material into the mixer plate, mixing in the dry state, dosed addition of moisture, mixing, adding additional crushed material - dusting, rolling granules, unloading the granulator plate.

The granular material is dried by the method of combined drying, and in particular, preliminary drying to a residual moisture content of 10% in the field of microwave currents and then final drying to a relative humidity of 1.0-3.0% by convection method. The granular material is pre-dispersed to isolate the desired fraction.

The pellets are fired in a rotary gas furnace at a temperature of 1370-1490 ° C (preferably 1400-1430 ° C).

Cool and produce the final sieving of the obtained granules into commercial fractions.

The granules obtained comply with all the requirements of GOST R 51761-2001 “Aluminosilicate Propants” and API RP60 “Methodological Recommendations for Testing High-Strength Proppants for Hydraulic Fracturing”.

Example 1

Take aluminosilicate raw materials with a ratio of components, wt.%: Al ₂ O ₃ 50, SiO ₂ 35.0 and Fe ₂ O ₃ 15.0. This composition of the starting material does not provide sufficient strength of the finished product after the final firing due to a decrease in the amount of the solid phase - mullite and, accordingly, an increase in the amount of the liquid phase, which reduces the strength of the product.

Example 2

Take aluminosilicate raw materials with a ratio of components, wt.%: Al ₂ O ₃ 55, SiO ₂ 30,0 and Fe ₂ O ₃ 10,0. The most optimal raw material for the production of high-strength granules is an aluminum-containing raw material with a given ratio of components. This composition of the raw material provides a sufficient fraction of the solid phase in the finished product - mullite, does not require high firing temperatures, has a low cost and wide distribution.

Example 3

Take aluminosilicate raw materials with a ratio of components, wt.%: Al ₂ O ₃ 60, SiO ₂ 25,0 and Fe ₂ O ₃ 5,0. This ratio of the components of the feedstock provides sufficient strength of the finished product, but is expensive and low-tech, as it requires high temperatures when firing products.

The use of the inventive methods of grinding and drying, and in particular the grinding of calcined raw materials in a centrifugal mill with an air separator and drying of the material after granulation by the combined method: drying in the microwave field to a residual moisture content of 10% and convection method to a residual moisture content of 1-3%, together contribute increase the strength of proppants by 6% (each by 3%). The effect of these manufacturing methods on the strength of the products is presented in the table.

Thus, the inventive method for producing refractory high-strength spherical granules (proppants) with the claimed ratio of the components of the feedstock and the methods used for grinding calcined raw materials and drying granular material allows to obtain granules of high strength, reduce energy consumption during the implementation of the method and, thereby, reduce the cost of production .

The method of obtaining refractory high-strength spherical granules (proppants)

Characteristics of proppants by examples
Table Example No. The percentage of destroyed granules of the fraction of 0.85-1.18 mm at 69 MPa, wt.% Grinding raw materials in a ball mill, drying only by convection Grinding of raw materials in a centrifugal mill, drying only by convection Grinding of raw materials in a centrifugal mill, drying by a combined method one 18.6 18.05 17.5 2 16.6 16.1 15.6 3 16.9 16,4 15.9

Claims (1)

A method for producing refractory high-strength ceramic granules (proppants), including calcining aluminosilicate raw materials, grinding, granulation with dosed moisture, dusting, rolling granules, drying, preliminary sieving, firing, final sieving, characterized in that aluminosilicate raw materials are used as starting material . the following component ratio, wt%: Al ₂ O ₃ - 50-60, SiO ₂ - 25-35, Fe ₂ O ₃ - 5-15, grinding of raw materials after calcination is carried out in a centrifugal air classifier mill, drying ranulirovannogo raw performed previously in the microwave currents to a relative humidity of 10.0% and a final drying is carried out by convection due to thermal radiation to a relative humidity of 1.0-3.0%.