Low-quality coal saving agent for cement clinker production and preparation method and application thereof

Abstract

The present application relates to cement clinker production admixture technical field, especially to a kind of coal-saving agent for coal combustion in cement clinker production process and preparation method thereof, the coal-saving agent can be directly added to coal, on the one hand, it can reduce the energy consumption of coal powder grinding process, more importantly, it can promote the coal powder with poor quality to release heat in a short time, and improve the use effect of low-quality coal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cement clinker production additives, and particularly relates to a low-quality coal saving agent for cement clinker production and a preparation method thereof. BACKGROUND

[0002] The production process of cement can be simply referred to as "two grinding and one burning", two grinding refers to raw material grinding and clinker grinding, and high-temperature burning is between the two grinding processes. The raw material grinding process consumes a large amount of energy, mainly because a large amount of energy is converted into sound energy and heat energy during grinding. The demand for coal in a cement kiln is high, but the effective utilization rate is very low. In industry, coal is usually ground into coal powder to improve the utilization rate of coal. The grinding efficiency of coal directly affects the utilization rate of coal. The finer the coal powder, the larger the contact area during coal combustion, the higher the heat energy released by the coal, and the utilization rate will also be improved. The current coal saving approach is mainly to add some grinding and coal saving agents to the raw material to reduce the energy consumption of the raw material in the grinding process and improve the grinding efficiency, and to add some coal saving components to improve the utilization rate of heat value, which indirectly saves coal. Such effect is not obvious, has little effect on the use of coal, and only improves the utilization rate of heat value generated by coal combustion.

[0003] With the decrease of resources and the increase of prices of natural high-quality coal, more and more cement kilns explore the use of low-quality coal as fuel. Although the use of combustion improver to improve the utilization efficiency of coal heat value is recorded in the prior art, the effects of coal saving agent and combustion improver are similar, but the requirements and composition of the coal saving agent for cement kiln and the combustion improver for other industrial kiln are completely different. Combustion improver is usually used in other fields that use coal to provide heat, but ordinary combustion improver is not suitable for cement production because of the particularity of cement production. The residual ash after coal powder combustion will enter the cement, and if the coal powder combustion is not sufficient, the quality of the cement will be affected, and the Cl - in the coal saving agent will also affect the performance of the cement, so a new cement suitable coal saving agent needs to be developed. In the cement production process, how to improve the effective utilization rate of coal is a key issue to reduce the energy carbon emission of the cement production industry.

[0004] The prior art CN113800796A discloses a cement raw material additive and a preparation method thereof, the cement raw material additive is prepared from the following raw materials in mass percentage: raw material decomposition promoter 10-17%, coal-saving agent 13-16%, grinding aid enhancer 6-9%, desulfurization active agent 10-14%, dispersing agent 0.1-0.3%; the balance is water, and the total amount is 100%; the raw material decomposition promoter is one or a mixture of several of oxalic acid, citric acid, sodium acetate or potassium acetate; the coal-saving agent is one or a mixture of several of polyol polymer, hydrogen peroxide or ethylene glycol; the grinding aid enhancer is one or a mixture of several of triethanolamine, glycerol, triisopropanolamine and diethanolamine; and the dispersing agent is one or a mixture of both of cetyltrimethylammonium bromide and sodium dodecyl sulfate. The cement raw material additive introduces a large amount of acidic substances in cement production, which has a negative impact on the quality control of cement clinker, and the coal-saving rate and raw material table time yield are low, the coal-saving efficiency is not ideal, the benefits brought by coal-saving may not offset the cost of raw material grinding aid, the effect of improving the quality of cement clinker is also limited, and it is not suitable for large-scale promotion. CN104119982A discloses a coal-saving agent for cement clinker rotary kiln clinker sintering and a preparation method thereof, the coal-saving agent is prepared from silicon-calcium slag by dealkalization and / or drying, and contains dicalcium silicate; the total weight of silicon dioxide and calcium oxide in the coal-saving agent is 70-77wt%; the density of the coal-saving agent is 2.9-3.1g / cm 3 , the loose bulk density is 0.9-1.3g / cm 3 , and the median particle size is 25-30μm; and the alkali content of the coal-saving agent is less than 1wt% based on the total weight of the coal-saving agent, and the water content of the coal-saving agent is less than 5wt% based on the amount of Na2O. The preparation steps of the coal-saving agent are numerous and the preparation conditions are relatively complex, the reaction needs to be carried out under high-temperature water conditions and the dewatering operation needs to be carried out by a filter press, and the technical parameters are difficult to control; the obtained finished product is a solid, and the dispersing is uneven during use, and the practicability is not strong.

[0005] Therefore, it is of important practical significance to develop a coal-saving agent for poor coal, promote the release of coal heat, release the heat of coal in a short time, and directly add the coal-saving agent to coal, so as to improve the quality of cement and realize the double-carbon target. SUMMARY

[0006] To solve the problems in the prior art, the present application provides a poor coal-saving agent for cement clinker production, the coal-saving agent of the present application is directly added to coal, the adding mode of the coal-saving agent is more convenient, the grinding aid coal-saving agent is added in the process of grinding coal into coal powder, which can reduce the energy consumption of the coal grinding process, and more importantly, promote the release of heat of poor coal powder in a short time and improve the use effect of low-quality coal.

[0007] Specifically, the low-quality coal-saving agent for cement clinker production is prepared from the following raw materials in parts by weight: glycerol residue 10-15 parts, sulfuric acid plant waste liquid 2-6 parts, penetrating agent 0.5-0.7 parts, mineralizing agent 0.5-1 part, dispersing agent 0.3-1 part, oxidizing agent 2-5 parts, desulfurizing agent 10-15 parts, and water 55-80 parts.

[0008] The coal-saving agent in the prior art is generally high in cost and low in coal-saving effect, and some coal-saving agents cannot even reduce the cost of coal, and the addition amount of the coal-saving agent is usually less than one thousandth, which makes it difficult for the coal-saving agent to be uniformly dispersed on the surface of coal, and the present application improves the burnout efficiency of coal powder by adding glycerol residue to the coal-saving agent containing alkali metal ions, the active group -OH on the surface of glycerol can also make the coal-saving agent exhibit good hydrophilicity, and the glycerol residue can also be used to improve the dispersibility of the coal-saving agent, so that the coal-saving agent is uniformly dispersed on the surface of coal. The organic components in the glycerol residue can form a certain amount of volatile matter in the coal powder, and the higher the content of volatile matter, the better the combustion effect of the coal powder. When high-ash coal is mixed with organic matter and burned, multiple different exothermic peaks will appear, and when the content of organic matter increases, the weight loss temperature will be advanced. Organic matter is easy to volatilize, and the higher the volatile matter, the better the ignition characteristics of the mixture. The glycerol residue can provide a high amount of organic matter volatilization for the combustion of coal powder. The glycerol residue will generate a certain amount of heat value after further combustion with coal powder, and the product of the glycerol residue does not contain harmful gases. The present application uses glycerol residue as the main component, which greatly improves the utilization rate of industrial waste, but the coal-saving agent prepared by using a large amount of glycerol residue is prone to stratification during storage, and the prepared cement clinker is poor in grindability. Through a large number of experiments, it is found that the addition of part of the sulfuric acid plant waste liquid together with the glycerol residue can solve the problem of poor storage stability, and can also improve the grindability of the cement clinker. It may be because the addition of the sulfuric acid plant waste liquid improves the combustion stability of the low-quality coal, and the ash brought in may change the tight structure of the clinker pellets.

[0009] Preferably, the penetrating agent is at least one of dodecyltrimethylammonium chloride and citric acid.

[0010] Preferably, the mineralizing agent is ferric citrate.

[0011] Preferably, the dispersing agent is at least one of sodium tripolyphosphate, sodium hexametaphosphate and sodium pyrophosphate.

[0012] The penetrating agent, the mineralizing agent and the dispersing agent of the present application can work synergistically to promote the dispersed combustion of low-quality coal and improve the heat release efficiency.

[0013] Preferably, the oxidizing agent is at least one of cerium nitrate, ammonium nitrate, iron nitrate, potassium permanganate. The coal-saving agent needs to add an oxidizing agent to improve the efficiency of the release of heat energy of coal. In the present application, the addition of cerium nitrate, ammonium nitrate, iron nitrate, potassium permanganate plays an oxidizing role, preferably cerium nitrate and potassium permanganate, the rare earth elements in cerium nitrate increase the catalytic activity of the reaction, and potassium permanganate has strong oxidizing properties and high oxidizing properties under both alkaline and acidic conditions.

[0014] Preferably, the desulfurizer is at least one of sodium phosphate, sodium nitrate, sodium nitrite, urea, ammonia, and calcium carbide slag. More preferably, the water content of the calcium carbide slag is 40-50%.

[0015] Preferably, the water is deionized water or tap water.

[0016] The present application also relates to a preparation method of the above-mentioned cement clinker production low-quality coal coal-saving agent, specifically comprising the following preparation steps:

[0017] 1) Stir and mix the glycerol residue and the waste liquid from a sulfuric acid plant uniformly to obtain material 1;

[0018] 2) Add the penetrant, mineralizer, and oxidizing agent into water in sequence, stir uniformly, then add the desulfurizer and stir uniformly to obtain material 2;

[0019] 3) Mix material 1 and material 2, add the dispersant, and ultrasonic dispersion, and the present application is obtained.

[0020] The present application also relates to the application of the above-mentioned cement clinker production low-quality coal coal-saving agent, specifically adding the coal-saving agent in the low-quality coal grinding process, preferably, the addition amount of the coal-saving agent is 0.03-0.09% of the mass of the low-quality coal.

[0021] The low-quality coal coal-saving agent of the present application can reduce the energy consumption of the low-quality coal grinding process, improve the low-quality coal grinding efficiency, further improve the combustion efficiency of the low-quality coal, and effectively reduce the apparent activation of the low-quality coal combustion, reduce the ignition point of the low-quality coal, and accelerate the combustion rate of the coke, accelerate the breaking of various bonds in the coal pyrolysis process, and improve the release speed of the coal volatile matter, thereby improving the utilization rate of the low-quality coal and saving energy. In addition, it has a very obvious improvement effect on sulfur fixation and dust reduction, increases the sulfur fixation amount in the coal slag or clinker, can make the black smoke of the boiler white, reduces the atmospheric environmental load, and reduces the cost of flue gas desulfurization of enterprises. DETAILED DESCRIPTION

[0022] The effect of the low-quality coal coal-saving agent of the present application is tested for permeability, coal dust ignition point, and cement kiln firing coal-saving rate. In examples 1-3 and comparative examples 1-2, the coal-saving agent is added in the low-quality coal grinding process at 0.06%, and the coal powder is obtained by grinding. In the blank example, no coal-saving agent is added in the low-quality coal grinding process.

[0023] The permeability test is as follows: 100 ml of the coal-saving agent is taken in a colorimetric tube, 10 g of coal powder is added, and the settlement of the coal powder in the coal-saving agent is observed to determine the permeability of the coal-saving agent.

[0024] The coal powder ignition point test is as follows: a thermogravimetric analyzer is used, and the same mass of blank coal powder and coal powder added with the coal-saving agent is heated from 30°C to 960°C at an air flow rate of 40 ml / min and a heating rate of 15°C / min, and the initial combustion point and the final combustion point are determined according to the thermogravimetric diagram.

[0025] The cement kiln firing test is as follows: the coal-saving agent is tested in a coal mill of a cement kiln, the coal-saving agent is added to the coal mill, and the ground coal powder is used for cement firing. The test period of each coal-saving agent sample is 7 days, the standard coal consumption (kg / t) = total standard coal consumption (kg) ÷ cement clinker amount (t), and the coal-saving rate = (blank example standard coal consumption - example or comparative example standard coal consumption) ÷ blank example standard coal consumption × 100%.

[0026] Example 1

[0027] The low-quality coal-saving agent is composed of the following raw materials in parts by weight: glycerol residue 12 parts, waste liquid from a sulfuric acid plant 4 parts, dodecyltrimethylammonium chloride 0.5 part, ferric citrate 0.5 part, sodium tripolyphosphate 0.5 part, cerium nitrate 3 parts, sodium nitrate 12 parts, and water 71.5 parts.

[0028] Example 2

[0029] The low-quality coal-saving agent is composed of the following raw materials in parts by weight: glycerol residue 10 parts, waste liquid from a sulfuric acid plant 3 parts, dodecyltrimethylammonium chloride 0.5 part, ferric citrate 0.7 part, sodium hexametaphosphate 0.5 part, ferric nitrate 3 parts, sodium nitrite 14 parts, and water 69.3 parts.

[0030] Example 3

[0031] The low-quality coal-saving agent is composed of the following raw materials in parts by weight: glycerol residue 14 parts, waste liquid from a sulfuric acid plant 3 parts, dodecyltrimethylammonium chloride 0.5 part, ferric citrate 0.7 part, sodium hexametaphosphate 0.5 part, potassium permanganate 3 parts, urea 12 parts, and water 71.3 parts.

[0032] Comparative Example 1

[0033] The coal-saving agent is composed of the following raw materials in parts by weight: glycerol residue 17 parts, dodecyltrimethylammonium chloride 0.5 part, ferric citrate 0.7 part, sodium hexametaphosphate 0.5 part, potassium permanganate 3 parts, urea 12 parts, and water 71.3 parts.

[0034] Comparative Example 2

[0035] The coal-saving agent is composed of the following raw materials in parts by weight: glycerin residue 14 parts, waste liquid from sulfuric acid plant 3 parts, dodecyl trimethyl ammonium chloride 1.2 parts, sodium hexametaphosphate 0.5 parts, potassium permanganate 3 parts, urea 12 parts, and water 71.3 parts.

[0036] It is detected that the pulverized coal in examples 1-3 is rapidly settled in the coal-saving agent, which shows that the coal-saving agent has strong permeability to coal and is beneficial to improve the internal combustion rate of the pulverized coal. The pulverized coal in comparative examples 1-2 is settled in the coal-saving agent, but the rate is lower than that of examples 1-3. Through analysis and calibration of the thermogravimetric analysis diagram, it is obtained that the initial combustion point and the final combustion point of the blank sample are 512.04℃ and 630.03℃ respectively, the initial combustion point and the final combustion point of the sample after adding the coal-saving agent of examples 1-3 are 509.56℃, 508.61℃, 509.68℃ and 628.51℃, 627.68℃, 627.26℃ respectively, and the initial combustion point and the final combustion point of the sample after adding the coal-saving agent of comparative examples 1-2 are 509.56℃, 509.38℃ and 628.48℃, 627.98℃ respectively. It is shown that the initial combustion point and the final combustion point of the pulverized coal after adding the coal-saving agent are reduced. The standard coal consumption of the blank sample without adding the coal-saving agent is 124.78kg / t, the standard coal consumption of examples 1-3 is 120.62kg / t, 121.21kg / t, 120.56kg / t respectively, and the standard coal consumption of comparative examples 1-2 is 121.89kg / t, 121.96kg / t respectively. Through test calculation of the loss on ignition, it is obtained that the coal-saving rates of the blank sample without adding the coal-saving agent, the pulverized coal using examples 1-3 and the pulverized coal using comparative examples 1-2 are 3.33%, 2.86%, 3.38%, 2.31%, 2.26% respectively.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some or all of the technical features; and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A coal-saving agent for producing low-quality coal in cement clinker production, characterized in that, It is composed of the following raw materials in parts by weight: 10-15 parts glycerol residue, 2-6 parts sulfuric acid plant waste liquid, 0.5-0.7 parts penetrant, 0.5-1 part mineralizer, 0.3-1 part dispersant, 2-5 parts oxidant, 10-15 parts desulfurizer, and 55-80 parts water. The penetrant is at least one of dodecyltrimethylammonium chloride and citric acid. The mineralizing agent is ferric citrate.

2. The low-quality coal saving agent for cement clinker production according to claim 1, characterized in that, The dispersant is at least one of sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate.

3. The low-quality coal saving agent for cement clinker production according to claim 1, characterized in that, The oxidant is at least one of cerium nitrate, ammonium nitrate, ferric nitrate, and potassium permanganate.

4. The low-quality coal saving agent for cement clinker production according to claim 1, characterized in that, The desulfurizing agent is at least one of urea, ammonia, and carbide slag.

5. The low-quality coal saving agent for cement clinker production according to claim 4, characterized in that, The water content of the carbide slag is 40-50%.

6. The low-quality coal saving agent for cement clinker production according to claim 1, characterized in that, The water is either deionized water or tap water.

7. The method for preparing the low-quality coal saving agent for cement clinker production according to any one of claims 1-6, characterized in that, The preparation steps include the following: 1) Mix the glycerol residue and sulfuric acid plant waste liquid evenly to obtain material 1; 2) Add the penetrant, mineralizer, and oxidant to the water in sequence, stir evenly, then add the desulfurizer and stir evenly to obtain material 2; 3) Mix material 1 and material 2, add dispersant, and ultrasonically disperse to obtain the final product.

8. The application of the low-quality coal saving agent for cement clinker production according to any one of claims 1-6, characterized in that, The coal-saving agent is added during the grinding process of low-quality coal.