Method for calcining limestone in pulverized coal rotary kiln

Abstract

The invention discloses a method for calcining limestone in a pulverized coal rotary kiln, and the processing method comprises the following steps: A, raw material preparation: selecting limestone with excellent quality and low impurity content as a main raw material, selecting high-quality pulverized coal as a fuel, the heat value of the pulverized coal is not lower than 5000 kcal / kg, the ash content is not higher than 10%, the limestone is crushed to the particle size of 0-5 mm, impurities and particles larger than 5 mm in the limestone are removed through screening equipment, the pulverized coal is dried to enable the water content of the pulverized coal to be lower than 1%, and then the pulverized coal is ground to the particle size of 0-0.074 mm so as to improve the combustion efficiency of the pulverized coal. Through raw material preparation, the quality of limestone and pulverized coal is ensured, a good foundation is provided for the subsequent calcination process, the uniformity of the materials can be improved through crushing and screening, the agglomeration and blockage phenomena are reduced, the combustion efficiency of the pulverized coal can be improved through drying and grinding, and the energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of calcining limestone in a coal powder rotary kiln, in particular to a method for calcining limestone in a coal powder rotary kiln. Background Art

[0002] Limestone is mainly composed of calcium carbonate, which is usually white or gray and relatively soft. It is mainly formed by marine biological deposition and chemical precipitation, and is widely distributed on the earth. In terms of building materials, it can be used in cement and lime production and as stone; in the metallurgical industry, it is a flux and slag-making agent for iron and steel making; in the chemical industry, it can produce calcium carbonate, soda ash, etc.; in the environmental protection field, it can be used for flue gas desulfurization and sewage treatment; in the agricultural field, it can improve acidic soil and be used as a feed additive. The protection of limestone resources requires reasonable mining and mine reclamation to achieve sustainable utilization. At present, the calcination of limestone mainly adopts traditional vertical kilns, Lipo kilns and other methods, but the current method of calcining limestone in coal powder rotary kilns has high energy consumption, high pollution, and unstable product quality, which affects people's use. For this reason, we propose a method for calcining limestone in coal powder rotary kilns. Summary of the invention

[0003] The purpose of the present invention is to provide a method for calcining limestone in a coal powder rotary kiln, which has the advantages of low energy consumption, low pollution and stable product quality, and solves the problem that the existing method for calcining limestone in a coal powder rotary kiln has high energy consumption, high pollution and unstable product quality, thus affecting people's use.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for calcining limestone in a coal powder rotary kiln, the processing method comprising the following steps: A. Raw material preparation: Select limestone with good quality and low impurity content as the main raw material. The main component of limestone is calcium carbonate, and its content should not be less than 90%. Select high-quality coal powder as fuel. The calorific value of coal powder should not be less than 5000 kcal / kg, and the ash content should not be higher than 10%. Crush the limestone to a particle size of 0-5mm, and remove impurities and particles larger than 5mm through screening equipment. Dry the coal powder to make its water content less than 1%, and then grind it to a particle size of 0-0.074mm to improve its combustion efficiency; B. Evenly mix: Put the crushed limestone and coal powder into the spiral mixer in a certain proportion. The mixing time should be reasonably adjusted according to the characteristics of the materials and the type of mixing equipment, generally 5-10 minutes. Then conduct quality inspection on the mixed materials. The mixed materials should have uniform color and no obvious stratification and agglomeration. If they do not meet the standards, re-production is required; C. Preheating treatment: The mixed materials are sent into the preheater. The preheating temperature is generally controlled at 200-300℃ and the preheating time is 10-15 minutes. During the preheating process, attention should be paid to controlling the residence time of the materials and the air flow speed to avoid overheating of the materials and the occurrence of ring formation. D. Rotary kiln calcination: The preheated materials are sent into the rotary kiln. The speed of the rotary kiln is generally controlled at 1-3r / min. The temperature in the kiln should be reasonably adjusted according to the characteristics of the limestone and product requirements, generally between 800-1000℃. During the calcination process, attention should be paid to controlling the atmosphere in the kiln. Generally, an oxidizing atmosphere is used to promote the decomposition reaction of the limestone. At the same time, the material distribution and combustion conditions in the kiln should be checked regularly, and the operating parameters should be adjusted in time to ensure the stability and efficiency of the calcination process; E. Cooling: The temperature of the calcined material is high and needs to be cooled to prevent the material from agglomerating and deteriorating during storage and transportation; F. Screening and grading: The cooled material is sent to the rotary vibrating screen for screening and grading; G. Quality inspection: Carry out quality inspection on the materials after screening and grading. The quality inspection items include calcium oxide content, carbon dioxide content, particle size, moisture content, etc. The inspection results should meet the relevant standards and requirements; H. Packaging and storage: Qualified materials should be packed in woven bags. The packaging should be tight and firm to prevent leakage and contamination during storage and transportation. During storage, attention should be paid to moisture-proof, sun-proof, and anti-deterioration. Materials should be stored in a dry, ventilated, and cool place to avoid contact with acids, alkalis, and other substances.

[0005] Preferably, a shock-absorbing base is provided at the bottom of the spiral mixer, a moving wheel is provided at the bottom of the shock-absorbing base, and a double brake is provided on the moving wheel.

[0006] Preferably, a dust hood is provided on the top of the rotary vibrating screen, a dust box is provided on the bottom of the rotary vibrating screen, a filter is provided in the inner cavity of the dust box, a fan is fixedly connected to the right side of the dust box, the air intake port of the fan is fixedly connected to the right side of the inner cavity of the dust box through a pipe, and the left side of the dust box is fixedly connected to the dust hood through a pipe.

[0007] Preferably, the preheater can be a vertical preheater or a Lippo preheater.

[0008] Preferably, the cooling method can be air cooling, water cooling or natural cooling, etc., which should be selected according to the characteristics of the material and production requirements. The temperature of the material after cooling should be reduced to an appropriate range, generally between 100-150°C, for subsequent processing.

[0009] Compared with the prior art, the present invention has the following beneficial effects: The present invention ensures the quality of limestone and coal powder through raw material preparation, and provides a good foundation for the subsequent calcination process. Crushing and screening can improve the uniformity of materials and reduce agglomeration and clogging phenomena. Drying and grinding can improve the combustion efficiency of coal powder and reduce energy consumption. Uniform mixing ensures the uniformity of materials and avoids local overheating or insufficient combustion. Good mixing can increase the reaction rate and improve product quality. Preheating treatment can remove moisture from materials and reduce subsequent energy consumption. The temperature of materials is increased, the decomposition reaction of limestone is accelerated, the fluidity of materials is improved, and the occurrence of clogging and ringing phenomena is reduced. The rotary kiln is used for calcination, and the rotary kiln can provide a uniform heating and reaction environment, improve the calcination efficiency and product quality, and can control the atmosphere and temperature in the kiln. degree, to achieve precise control of the reaction, with a large production capacity, can meet the needs of large-scale production, through cooling, can prevent materials from caking and deterioration during storage and transportation, to ensure product quality, through screening and grading, the materials can be divided into different particle size levels, to meet different product requirements, improve the added value of the product, can remove impurities and unqualified materials, improve the purity and quality of the product, through quality testing, to ensure that product quality meets relevant standards and requirements, improve the market competitiveness of the product, can timely discover and solve problems, avoid the occurrence of quality accidents, provide a basis for the optimization of the production process, through packaging and storage, protect the product from the influence of the external environment, ensure the stability of product quality, facilitate product storage and transportation, and improve logistics efficiency. DETAILED DESCRIPTION

[0010] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0011] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0012] A method for calcining limestone in a coal powder rotary kiln, the processing method comprising the following steps: A. Raw material preparation: Select limestone with good quality and low impurity content as the main raw material. The main component of limestone is calcium carbonate, and its content should not be less than 90%. Select high-quality coal powder as fuel. The calorific value of coal powder should not be less than 5000 kcal / kg, and the ash content should not be higher than 10%. Crush the limestone to a particle size of 0-5mm, and remove impurities and particles larger than 5mm through screening equipment. Dry the coal powder to make its water content less than 1%, and then grind it to a particle size of 0-0.074mm to improve its combustion efficiency; B. Evenly mix: Put the crushed limestone and coal powder into the spiral mixer in a certain proportion. The mixing time should be reasonably adjusted according to the characteristics of the materials and the type of mixing equipment, generally 5-10 minutes. Then conduct quality inspection on the mixed materials. The mixed materials should have uniform color and no obvious stratification and agglomeration. If they do not meet the standards, re-production is required; C. Preheating treatment: The mixed materials are sent into the preheater. The preheating temperature is generally controlled at 200-300℃ and the preheating time is 10-15 minutes. During the preheating process, attention should be paid to controlling the residence time of the materials and the air flow speed to avoid overheating of the materials and the occurrence of ring formation. D. Rotary kiln calcination: The preheated materials are sent into the rotary kiln. The speed of the rotary kiln is generally controlled at 1-3r / min. The temperature in the kiln should be reasonably adjusted according to the characteristics of the limestone and product requirements, generally between 800-1000℃. During the calcination process, attention should be paid to controlling the atmosphere in the kiln. Generally, an oxidizing atmosphere is used to promote the decomposition reaction of the limestone. At the same time, the material distribution and combustion conditions in the kiln should be checked regularly, and the operating parameters should be adjusted in time to ensure the stability and efficiency of the calcination process; E. Cooling: The temperature of the calcined material is high and needs to be cooled to prevent the material from agglomerating and deteriorating during storage and transportation; F. Screening and grading: The cooled material is sent to the rotary vibrating screen for screening and grading; G. Quality inspection: Carry out quality inspection on the materials after screening and grading. The quality inspection items include calcium oxide content, carbon dioxide content, particle size, moisture content, etc. The inspection results should meet the relevant standards and requirements; H. Packaging and storage: Qualified materials should be packed in woven bags. The packaging should be tight and firm to prevent leakage and contamination during storage and transportation. During storage, attention should be paid to moisture-proof, sun-proof, and anti-deterioration. Materials should be stored in a dry, ventilated, and cool place to avoid contact with acids, alkalis, and other substances.

[0013] A shock-absorbing base is provided at the bottom of the spiral mixer, a moving wheel is provided at the bottom of the shock-absorbing base, a double brake is provided on the moving wheel, a dust hood is provided on the top of the rotary vibrating screen, a dust collecting box is provided at the bottom of the rotary vibrating screen, a filter is provided in the inner cavity of the dust collecting box, a fan is fixedly connected to the right side of the dust collecting box, the air intake of the fan is fixedly connected to the right side of the inner cavity of the dust collecting box through a pipe, and the left side of the dust collecting box is fixedly connected to the dust hood through a pipe. The preheater can adopt a vertical preheater or a Lipo preheater, and the cooling method can be air cooling, water cooling or natural cooling, etc., which should be selected according to the characteristics of the material and the production requirements. The temperature of the material after cooling should be reduced to an appropriate range, generally between 100-150°C, for subsequent processing.

[0014] When in use, raw material preparation can ensure the quality of limestone and coal powder, providing a good foundation for the subsequent calcination process. Crushing and screening can improve the uniformity of materials and reduce agglomeration and clogging. Drying and grinding can improve the combustion efficiency of coal powder and reduce energy consumption. Even mixing can ensure the uniformity of materials and avoid local overheating or incomplete combustion. Good mixing can increase the reaction rate and improve product quality. Preheating treatment can remove moisture from materials and reduce subsequent energy consumption. It can also increase the temperature of materials, accelerate the decomposition reaction of limestone, improve the fluidity of materials, and reduce the occurrence of clogging and ringing. Rotary kiln calcination can provide a uniform heating and reaction environment, improve calcination efficiency and product quality, and control the atmosphere and Temperature, to achieve precise control of the reaction, with a large production capacity, can meet the needs of large-scale production, through cooling, can prevent materials from caking and deterioration during storage and transportation, to ensure product quality, through screening and grading, the materials are divided into different particle size levels, to meet different product requirements, improve the added value of the product, can remove impurities and unqualified materials, improve the purity and quality of the product, through quality testing, to ensure that product quality meets relevant standards and requirements, improve the market competitiveness of the product, can timely discover and solve problems, avoid the occurrence of quality accidents, provide a basis for the optimization of the production process, through packaging and storage, protect the product from the influence of the external environment, ensure the stability of product quality, facilitate product storage and transportation, and improve logistics efficiency.

[0015] Importantly, it should be noted that the construction and arrangement of the present application shown in a number of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, changes in orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete element may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to an alternative embodiment. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also equivalent structure. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present invention. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0016] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment may not be described (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those features that are not relevant to implementing the invention).

[0017] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for calcining limestone in a coal powder rotary kiln, characterized in that: The processing method comprises the following steps: A. Raw material preparation: Select limestone with good quality and low impurity content as the main raw material. The main component of limestone is calcium carbonate, and its content should not be less than 90%. Select high-quality coal powder as fuel. The calorific value of coal powder should not be less than 5000 kcal / kg, and the ash content should not be higher than 10%. Crush the limestone to a particle size of 0-5mm, and remove impurities and particles larger than 5mm through screening equipment. Dry the coal powder to make its water content less than 1%, and then grind it to a particle size of 0-0.074mm to improve its combustion efficiency; B. Evenly mix: Put the crushed limestone and coal powder into the spiral mixer in a certain proportion. The mixing time should be reasonably adjusted according to the characteristics of the materials and the type of mixing equipment, generally 5-10 minutes. Then conduct quality inspection on the mixed materials. The mixed materials should have uniform color and no obvious stratification and agglomeration. If they do not meet the standards, re-production is required; C. Preheating treatment: The mixed materials are sent into the preheater. The preheating temperature is generally controlled at 200-300℃ and the preheating time is 10-15 minutes. During the preheating process, attention should be paid to controlling the residence time of the materials and the air flow speed to avoid overheating of the materials and the occurrence of ring formation. D. Rotary kiln calcination: The preheated materials are sent into the rotary kiln. The speed of the rotary kiln is generally controlled at 1-3r / min. The temperature in the kiln should be reasonably adjusted according to the characteristics of the limestone and product requirements, generally between 800-1000℃. During the calcination process, attention should be paid to controlling the atmosphere in the kiln. Generally, an oxidizing atmosphere is used to promote the decomposition reaction of the limestone. At the same time, the material distribution and combustion conditions in the kiln should be checked regularly, and the operating parameters should be adjusted in time to ensure the stability and efficiency of the calcination process; E. Cooling: The temperature of the calcined material is high and needs to be cooled to prevent the material from agglomerating and deteriorating during storage and transportation; F. Screening and grading: The cooled material is sent to the rotary vibrating screen for screening and grading; G. Quality inspection: Carry out quality inspection on the materials after screening and grading. The quality inspection items include calcium oxide content, carbon dioxide content, particle size, moisture content, etc. The inspection results should meet the relevant standards and requirements; H. Packaging and storage: Qualified materials should be packed in woven bags. The packaging should be tight and firm to prevent leakage and contamination during storage and transportation. During storage, attention should be paid to moisture-proof, sun-proof, and anti-deterioration. Materials should be stored in a dry, ventilated, and cool place to avoid contact with acids, alkalis, and other substances.

2. The method for calcining limestone in a pulverized coal rotary kiln according to claim 1, characterized in that: The bottom of the spiral mixer is provided with a shock-absorbing base, the bottom of the shock-absorbing base is provided with a moving wheel, and the moving wheel is provided with a double brake.

3. The method for calcining limestone in a pulverized coal rotary kiln according to claim 1, characterized in that: A dust hood is provided on the top of the rotary vibrating screen, a dust box is provided on the bottom of the rotary vibrating screen, a filter is provided in the inner cavity of the dust box, a fan is fixedly connected to the right side of the dust box, an air intake port of the fan is fixedly connected to the right side of the inner cavity of the dust box through a pipe, and the left side of the dust box is fixedly connected to the dust hood through a pipe.

4. The method for calcining limestone in a pulverized coal rotary kiln according to claim 1, characterized in that: The preheater can be a vertical preheater or a Lippo preheater.

5. The method for calcining limestone in a pulverized coal rotary kiln according to claim 1, characterized in that: The cooling method can be air cooling, water cooling or natural cooling, etc., which should be selected according to the characteristics of the material and production requirements. The temperature of the material after cooling should be reduced to an appropriate range, generally between 100-150°C, for subsequent processing.