A composite ceramsite and its production process

Abstract

The present invention provides a composite ceramsite, which comprises a porous inner core and a hard outer shell with a mass ratio of (0.5 - 1.5):1; wherein, the raw materials of the porous inner core include a first ceramic raw material, rigid rubber waste and flexible rubber waste with a mass ratio of 100:(10 - 20):(1 - 10); the raw material of the hard outer shell is a second ceramic raw material. At the same time, the present invention also provides a production process for the composite ceramsite.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas exploitation, and specifically, to a composite ceramsite and its production process. Background Art

[0002] During the exploitation of deep oil and gas wells, after fracturing treatment of high closure pressure and low permeability deposits, the oil and gas-bearing rock formations are cracked, and the oil and gas converge from the channels formed by the cracks. The ceramsite support material enters the formation together with the high-pressure solution and fills the rock fractures, playing a role in supporting the fractures from closing due to stress release, thereby maintaining high conductivity, enabling the smooth flow of oil and gas, and increasing production. Practice has proved that oil wells fractured with ceramsite proppants can increase production by 30 - 50%, and can also extend the service life of oil and gas wells.

[0003] The ceramsite proppant sintered from high-quality bauxite and other raw materials is a substitute for natural quartz sand, glass beads, metal balls and other fracturing proppants. For example: The low-density and high-strength ceramsite proppant coated with silicon dioxide and its preparation method disclosed in Chinese Patent CN113956864A uses the ceramsite proppant as the core, and deposits silicon dioxide on the surface of the ceramsite proppant to form a silicon dioxide-coated ceramsite proppant structure. However, in the technical solution disclosed in Chinese Patent CN113956864A, with the ceramsite proppant as the core, carbon dioxide is deposited on the surface of the ceramsite to form a shell, and this core-shell structure is not stable. At the same time, using tetraethyl orthosilicate as the raw material, the cost is too high.

[0004] In order to solve the above problems, people have been seeking an ideal technical solution. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art, and thus provide a composite ceramsite and its production process.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A composite ceramsite includes a porous inner core and a hard outer shell with a mass ratio of (0.5 - 1.5):1; wherein, the raw materials of the porous inner core include a first ceramic raw material, rigid rubber waste and flexible rubber waste with a mass ratio of 100:(10 - 20):(1 - 10); the raw material of the hard outer shell is a second ceramic raw material.

[0008] In an oxygen-rich atmosphere with a flow rate of 50 - 100 ml / min, at a heating rate of 5 - 10 °C / min, heating from 25 °C to 900 °C, the rigid rubber waste loses 40% - 60% of its weight, and the flexible rubber waste loses 60% - 90% of its weight.

[0009] The first ceramic raw material and the second ceramic raw material are one or a combination of more than one of coal gangue, potassium feldspar, mullite, dolomite, wollastonite, tuff, quartz, clay, bauxite, kaolin, and alunite.

[0010] The Shore A hardness of the hard rubber waste is 60 - 90, and the Shore A hardness of the flexible rubber waste is 10 - 50.

[0011] A production process of the composite ceramsite includes the following steps:

[0012] (1) Pretreat the rigid rubber waste and the flexible rubber waste;

[0013] (2) Pretreat the first ceramic raw material and the second ceramic raw material;

[0014] (3) Granulate and sinter the pretreated rigid rubber waste, flexible rubber waste, and the first ceramic raw material to obtain a porous inner core;

[0015] (4) Uniformly spray the pretreated second ceramic raw material on the surface of the porous inner core, sinter, cool, and screen to obtain the product.

[0016] In step (1), take the hard rubber waste and successively perform cleaning, cutting, and pulverizing to obtain silicone rubber particles, and take the flexible rubber waste and perform cutting and melting to obtain liquid rubber.

[0017] In step (2), take the first ceramic raw material and the second ceramic raw material respectively and perform crushing and ball milling to obtain the first ceramic particles and the second ceramic particles; among them, the particle size of the first ceramic particles is less than 70 μm, and the particle size of the second ceramic particles is less than 200 nm.

[0018] The sintering regime in step (3): Under a vacuum environment, heat up to 300 - 900 °C and sinter in vacuum for 5 - 30 min, fill with oxygen and continue sintering for 5 - 10 min, then evacuate, and continue heating up to 900 - 1100 °C and sinter for 5 - 30 min.

[0019] In step (4), uniformly spray the pretreated second ceramic raw material on the surface of the porous inner core, sinter at 1300 - 1400 °C for 20 - 50 s, cool, and screen to obtain the product.

[0020] The present invention has outstanding substantial features and remarkable progress compared with the prior art. Specifically, for the composite ceramsite provided by the present invention, rubber waste and ceramic raw materials are used to prepare a porous inner core, which not only utilizes the rubber waste to form a porous structure, but also makes full use of the reinforcing oxides in the rubber; at the same time, a closed ceramic hard shell is formed on the surface of the porous inner core to improve the strength of the composite ceramsite. Specific Embodiments

[0021] The technical solution of the present invention will be further described in detail through specific embodiments. In the following embodiments, coal gangue is a solid waste discharged during the coal mining process and coal washing process, and its main components are as follows: SiO2 60% - 65%, Al2O3 16% - 18%, Fe2O3 12.45% - 14.27%, CaO 0.42% - 2.32%, MgO 1.40% - 2.41%, TiO2 2.50% - 4%, P2O5 0.007% - 0.24%, K2O + Na2O 1.4% - 3.9%, V2O5 0.008% - 0.03%; the main components of potassium feldspar are as follows: SiO2 60.0% - 68.0%, Al2O3 15.0% - 22.0%, K2O 9.05% - 15.0%, Na2O 2.00% - 2.55%. The main components of mullite are as follows: Al2O3 42% - 45%, Fe2O3 ≤ 1.0%, SiO2 49% - 55%, Na2O ≤ 4.0%; the main component of dolomite is CaMg(CO3)2; the main component of wollastonite is Ca3〔Si3O9〕; the main components of tuff are as follows: SiO2 72% - 74%, Al2O3 15% - 18%, Na2O 1.5% - 2.0%, K2O 7.0% - 9.0%, Fe2O3 < 0.20%, CaO < 0.5%, MgO < 0.3%, loss on ignition < 2.5%; the main component of quartz is SiO2; the main components in clay are as follows: SiO2 32% - 38%, Al2O3 42% - 50%; the rigid silicone rubber waste can be waste from special printing silicone rubber, ceramic rubber tubes, rubber treads, etc.; the flexible rubber waste can be waste from liquid silicone rubber for medical devices / electronic component seals, damping silicone rubber waste. Example

[0022] A composite ceramsite includes a porous inner core and a rigid outer shell with a mass ratio of (0.5 - 1.5):1 and a volume ratio of (3 - 6):1; wherein, the raw materials of the porous inner core include a first ceramic raw material, rigid rubber waste, and flexible rubber waste with a mass ratio of 100:(10 - 20):(1 - 10); the raw material of the rigid outer shell is a second ceramic raw material.

[0023] In an oxygen-rich atmosphere with a flow rate of 50 - 100 ml / min, at a heating rate of 5 - 10 °C / min, heating from 25 °C to 900 °C, the rigid rubber waste loses 40% - 60% in weight, and the flexible rubber waste loses 60% - 90% in weight. Among them, the oxygen-rich atmosphere can directly use air.

[0024] The first ceramic raw material and the second ceramic raw material have the same composition. By mass fraction, the first ceramic raw material and the second ceramic raw material include 13 parts of potassium feldspar, 22 parts of mullite, and 65 parts of lightly burned clay.

[0025] The Shore A hardness of hard rubber waste is 60 - 90, and the Shore A hardness of flexible rubber waste is 10 - 50.

[0026] A production process of the composite ceramsite includes the following steps:

[0027] (1) Pretreat the rigid rubber waste and flexible rubber waste; take the hard rubber waste and perform cleaning, cutting, and pulverizing in sequence to obtain silicone rubber particles, and take the flexible rubber waste and perform cutting and melting to obtain liquid rubber.

[0028] (2) Pretreat the first ceramic raw material and the second ceramic raw material; take the first ceramic raw material and the second ceramic raw material and perform crushing and ball milling respectively to obtain the first ceramic particles and the second ceramic particles; wherein, the particle size of the first ceramic particles is less than 70 μm, and the particle size of the second ceramic particles is less than 200 nm.

[0029] (3) Granulate the pretreated rigid rubber waste, flexible rubber waste, and the first ceramic raw material, and under a vacuum environment, heat up to 300 - 900 °C for vacuum sintering for 5 - 30 min, fill in oxygen and continue sintering for 5 - 10 min, then evacuate the vacuum, continue to heat up to 900 - 1100 °C for sintering for 5 - 30 min to obtain a porous inner core;

[0030] (4) Uniformly spray the pretreated second ceramic raw material on the surface of the porous inner core, sinter at 1300 - 1400 °C for 20 - 50 s, cool and screen to obtain the product.

[0031] Example 1

[0032] A composite ceramsite includes a porous inner core and a hard outer shell; wherein, the raw materials of the porous inner core include the first ceramic raw material, rigid rubber waste, and flexible rubber waste with a mass ratio of 100:13:5; the raw material of the hard outer shell is the second ceramic raw material; the mass ratio of the raw materials of the porous inner core and the hard outer shell is 1.2:1.

[0033] A production process of the composite ceramsite includes the following steps:

[0034] (1) Pretreat the rigid rubber waste and flexible rubber waste; take the hard rubber waste and perform cleaning, cutting, and pulverizing in sequence to obtain silicone rubber particles, and take the flexible rubber waste and perform cutting and melting to obtain liquid rubber.

[0035] Among them, the rigid rubber waste is rubber tread waste with a Shore hardness of 71, and the flexible rubber waste is damping silicone waste with a Shore hardness of 15. In an air atmosphere with a flow rate of 50 ml / min, a thermogravimetric analysis is carried out by heating from 25°C to 900°C at a heating rate of 10°C / min. The rigid rubber waste loses 57.2% in weight, and the flexible rubber waste loses 69.5% in weight.

[0036] (2)Pre-treat the first ceramic raw material and the second ceramic raw material; take the first ceramic raw material and the second ceramic raw material respectively for crushing and ball milling to obtain the first ceramic particles and the second ceramic particles.

[0037] Among them, the first ceramic raw material and the second ceramic raw material have the same composition. By mass fraction, the first ceramic raw material and the second ceramic raw material include 13 parts of potassium feldspar, 22 parts of mullite, and 65 parts of lightly burned clay. The particle size of the first ceramic particles is less than 70 μm, and the particle size of the second ceramic particles is less than 200 nm.

[0038] (3)Granulate the pre-treated rigid rubber waste, flexible rubber waste and the first ceramic raw material with a particle size of 70 - 80 mesh. In a vacuum environment, heat up to 500 - 600°C and sinter in vacuum for 20 min, then fill with oxygen and continue sintering for 10 min, and then evacuate the vacuum and continue heating up to 900 - 1100°C and sinter for 15 min to obtain a porous inner core with a particle size of 40 - 50 mesh.

[0039] (4)Evenly spray the pre-treated second ceramic raw material on the surface of the porous inner core, sinter at 1300 - 1400°C for 30 s, cool and screen to obtain composite ceramsite with a particle size of 30 - 50 mesh.

[0040] Referring to SY 17125 - 2019 Fracturing Proppant Performance Index and Evaluation Test Method, the performance of the fracturing proppant obtained in Example 1 is detected. The bulk density is 1.65 g / cm3; the apparent density is 2.89 g / cm3; the breakage rate at a closure pressure of 86 MPa is 4.0%.

[0041] Example 2

[0042] A composite ceramsite includes a porous inner core and a hard outer shell; among them, the raw materials of the porous inner core include the first ceramic raw material, rigid rubber waste and flexible rubber waste with a mass ratio of 100:15:5; the raw material of the hard outer shell is the second ceramic raw material; the mass ratio of the raw materials of the porous inner core and the hard outer shell is 1.2:1.

[0043] A production process of the composite ceramsite includes the following steps:

[0044] (1) Pretreat the rigid rubber waste and the flexible rubber waste; take the hard rubber waste and perform cleaning, cutting, and pulverization in sequence to obtain silicone rubber particles, and take the flexible rubber waste for cutting and melting to obtain liquid rubber.

[0045] Among them, the rigid rubber waste uses rubber tread waste with a Shore hardness of 71, and the flexible rubber waste uses damping silica gel waste with a Shore hardness of 15; in an air atmosphere with a flow rate of 50 ml / min, at a heating rate of 10 °C / min, heat the sample from 25 °C to 900 °C for thermogravimetric analysis. The rigid rubber waste loses 57.2% of its weight, and the flexible rubber waste loses 69.5% of its weight.

[0046] (2) Pretreat the first ceramic raw material and the second ceramic raw material; take the first ceramic raw material and the second ceramic raw material respectively for crushing and ball milling to obtain the first ceramic particles and the second ceramic particles.

[0047] Among them, the first ceramic raw material and the second ceramic raw material have the same composition. By mass fraction, the first ceramic raw material and the second ceramic raw material include 13 parts of potassium feldspar, 22 parts of mullite, and 65 parts of lightly burned clay. The particle size of the first ceramic particles is less than 70 μm, and the particle size of the second ceramic particles is less than 200 nm.

[0048] (3) Granulate the pretreated rigid rubber waste, flexible rubber waste, and the first ceramic raw material with a particle size of 70 - 80 mesh. In a vacuum environment, heat up to 500 - 600 °C for vacuum sintering for 5 - 30 min, then fill with oxygen and continue sintering for 10 min, and then evacuate, continue heating up to 900 - 1100 °C for sintering for 20 min to obtain a porous inner core with a particle size of 40 - 50 mesh.

[0049] (4) Uniformly spray the pretreated second ceramic raw material on the surface of the porous inner core, sinter at 1300 - 1400 °C for 40 s, cool and screen to obtain composite ceramsite with a particle size of 30 - 50 mesh.

[0050] Refer to SY 17125 - 2019 Fracturing Proppant Performance Index and Evaluation Test Method to detect the performance of the fracturing proppant obtained in Example 2. The bulk density is 1.62 g / cm3; the apparent density is 2.82 g / cm3; the crushing rate at a closure pressure of 86 MPa is 4.1%.

[0051] Example 3

[0052] A composite ceramsite, comprising a porous inner core and a hard outer shell; among them, the raw materials of the porous inner core include the first ceramic raw material, rigid rubber waste, and flexible rubber waste with a mass ratio of 100:10:5; the raw material of the hard outer shell is the second ceramic raw material; the mass ratio of the raw materials of the porous inner core and the hard outer shell is 1.2:1.

[0053] A production process of the composite ceramsite, which comprises the following steps:

[0054] (1) Pretreat the rigid rubber waste and flexible rubber waste; take the hard rubber waste and carry out cleaning, cutting, and pulverizing in sequence to obtain silicone rubber particles, and take the flexible rubber waste for cutting and melting to obtain liquid rubber.

[0055] Among them, the rigid rubber waste uses rubber tread waste with a Shore hardness of 71, and the flexible rubber waste uses damping silica gel waste with a Shore hardness of 15; in an air atmosphere with a flow rate of 50 ml / min, at a heating rate of 10 °C / min, heat weight analysis is carried out from 25 °C to 900 °C, and the rigid rubber waste loses 57.2% in weight, and the flexible rubber waste loses 69.5% in weight.

[0056] (2) Pretreat the first ceramic raw material and the second ceramic raw material; take the first ceramic raw material and the second ceramic raw material respectively for crushing and ball milling to obtain the first ceramic particles and the second ceramic particles.

[0057] Among them, the first ceramic raw material and the second ceramic raw material have the same composition. By mass, the first ceramic raw material and the second ceramic raw material include 13 parts of potassium feldspar, 22 parts of mullite, and 65 parts of lightly burned clay. The particle size of the first ceramic particles is less than 70 μm, and the particle size of the second ceramic particles is less than 200 nm.

[0058] (3) Granulate the pretreated rigid rubber waste, flexible rubber waste, and the first ceramic raw material with a particle size of 70 - 80 mesh, heat up to 500 - 600 °C in a vacuum environment for vacuum sintering for 15 min, fill in oxygen and continue sintering for 10 min, then evacuate, and continue heating up to 900 - 1100 °C for sintering for 30 min to obtain a porous inner core with a particle size of 40 - 50 mesh.

[0059] (4) Uniformly spray the pretreated second ceramic raw material on the surface of the porous inner core, sinter at 1300 - 1400 °C for 25 s, cool and screen to obtain the composite ceramsite with a particle size of 30 - 50 mesh.

[0060] Referring to SY 17125 - 2019 Performance Index and Evaluation Test Method of Fracturing Proppants, the performance of the fracturing proppants obtained in Example 3 is detected. The bulk density is 1.65 g / cm3; the apparent density is 2.93 g / cm3; the crushing rate at a closing pressure of 86 MPa is 4.0%.

[0061] Example 4

[0062] A composite ceramsite, comprising a porous inner core and a hard outer shell; wherein, the raw materials of the porous inner core include a first ceramic raw material, rigid rubber waste and flexible rubber waste with a mass ratio of 100:13:7; the raw material of the hard outer shell is a second ceramic raw material; the mass ratio of the raw materials of the porous inner core and the hard outer shell is 1.2:1.

[0063] A production process of the composite ceramsite, comprising the following steps:

[0064] (1) Pretreat the rigid rubber waste and the flexible rubber waste; take the hard rubber waste and perform cleaning, cutting and crushing in sequence to obtain silicone rubber particles, and take the flexible rubber waste for cutting and melting to obtain liquid rubber.

[0065] Among them, the rigid rubber waste uses rubber tread waste with a Shore hardness of 71, and the flexible rubber waste uses damping silicone rubber waste with a Shore hardness of 15; in an air atmosphere with a flow rate of 50 ml / min, at a heating rate of 10 °C / min, heat weight analysis is carried out from 25 °C to 900 °C, and the rigid rubber waste loses 57.2% of its weight, and the flexible rubber waste loses 69.5% of its weight.

[0066] (2) Pretreat the first ceramic raw material and the second ceramic raw material; take the first ceramic raw material and the second ceramic raw material and perform crushing and ball milling respectively to obtain first ceramic particles and second ceramic particles.

[0067] Among them, the first ceramic raw material and the second ceramic raw material have the same composition. By mass fraction, the first ceramic raw material and the second ceramic raw material include 13 parts of potassium feldspar, 22 parts of mullite and 65 parts of lightly burned clay. The particle size of the first ceramic particles is less than 70 μm, and the particle size of the second ceramic particles is less than 200 nm.

[0068] (3) Granulate the pretreated rigid rubber waste, flexible rubber waste and the first ceramic raw material with a particle size of 70-80 mesh, heat to 800-900 °C in a vacuum environment and sinter in vacuum for 5 min, fill with oxygen and continue sintering for 10 min, then evacuate, continue heating to 900-1100 °C and sinter for 15 min to obtain a porous inner core with a particle size of 40-50 mesh.

[0069] (4) Uniformly spray the pretreated second ceramic raw material on the surface of the porous inner core, sinter at 1300-1400 °C for 30 s, cool and screen to obtain the composite ceramsite with a particle size of 30-50 mesh.

[0070] Referring to SY 17125-2019 Performance Index and Evaluation Test Method for Fracturing Proppants, the performance of the fracturing proppant obtained in Example 4 is detected. The bulk density is 1.60 g / cm3; the apparent density is 2.83 g / cm3; the crushing rate at a closing pressure of 86 MPa is 4.1%.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements on some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A composite ceramsite, characterized in that: it comprises a porous inner core and a hard outer shell with a mass ratio of (0.5 - 1.5):1; wherein, the raw materials of the porous inner core include a first ceramic raw material, rigid rubber waste, and flexible rubber waste with a mass ratio of 100:(10 - 20):(1 - 10); the raw material of the hard outer shell is a second ceramic raw material; the Shore A hardness of the rigid rubber waste is 60 - 90, and the Shore A hardness of the flexible rubber waste is 10 - 50; The production process of the composite ceramsite, which comprises the following steps: (1) Pretreat the rigid rubber waste and the flexible rubber waste; (2) Pretreat the first ceramic raw material and the second ceramic raw material; (3) Granulate and sinter the pretreated rigid rubber waste, flexible rubber waste, and the first ceramic raw material to obtain a porous inner core; sintering regime: in a vacuum environment, heat up to 300 - 900 °C and sinter in vacuum for 5 - 30 min, fill with oxygen and continue sintering for 5 - 10 min, then evacuate the vacuum and continue heating up to 900 - 1100 °C and sinter for 5 - 30 min; (4) Uniformly spray the pretreated second ceramic raw material on the surface of the porous inner core, sinter, cool, and screen to obtain.

2. The composite ceramsite according to claim 1, characterized in that: In an oxygen-rich atmosphere with a flow rate of 50 - 100 ml / min, at a heating rate of 5 - 10 °C / min, heating from 25 °C to 900 °C, the rigid rubber waste loses 40% - 60% in weight, and the flexible rubber waste loses 60% - 90% in weight.

3. The composite ceramsite according to claim 1 or 2, characterized in that: The first ceramic raw material and the second ceramic raw material are one or a combination of more of coal gangue, potassium feldspar, mullite, dolomite, wollastonite, tuff, quartz, clay, bauxite, kaolin, and alunite.

4. The composite ceramsite according to claim 1, characterized in that: In step (1), take the rigid rubber waste and successively carry out cleaning, cutting, and crushing to obtain silicone rubber particles, and take the flexible rubber waste and carry out cutting and melting to obtain liquid rubber.

5. The composite ceramsite according to claim 1, characterized in that: In step (2), take the first ceramic raw material and the second ceramic raw material and respectively carry out crushing and ball milling to obtain first ceramic particles and second ceramic particles; wherein, the particle size of the first ceramic particles is less than 70 μm, and the particle size of the second ceramic particles is less than 200 nm.

6. The composite ceramsite according to claim 1, characterized in that: In step (4), uniformly spray the pretreated second ceramic raw material on the surface of the porous inner core, sinter at 1300 - 1400 °C for 20 - 50 s, cool, and screen to obtain.