CN108585552B

CN108585552B - Roasting process of active lime in rotary kiln

Info

Publication number: CN108585552B
Application number: CN201810138124.4A
Authority: CN
Inventors: 李文康; 张宸宇; 欧西江
Original assignee: Guangxi Huayang Mineral Source Co ltd
Current assignee: Guangxi Huayang Mineral Source Co ltd
Priority date: 2018-02-10
Filing date: 2018-02-10
Publication date: 2021-06-01
Anticipated expiration: 2038-02-10
Also published as: CN108585552A

Abstract

The invention provides a roasting process of active lime in a rotary kiln, which relates to the technical field of building material production, and comprises the following steps: (1) the method comprises the steps of (1) raw material pretreatment, (2) preparation of an additive, (3) preparation of limestone powder, (4) primary calcination, (5) secondary calcination and (6) discharging. The production process of the active lime does not add and generate any harmful substances from the used raw materials to the process, the lime with high activity is prepared by adding the additive and a scientific and reasonable production process, and simultaneously, the lime can keep high activity for a long time.

Description

Roasting process of active lime in rotary kiln

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of building material production, in particular to a roasting process of active lime in a rotary kiln.

[ background of the invention ]

At present, the situation of excess capacity of a cement market is gradually intensified in recent years, the cement market is continuously low, the cement price is greatly reduced, and partial cement plants are in a semi-stop state. The active lime is used as a basic material in the industries of smelting, chemical engineering, construction, medical treatment and health, thermal power plant desulfurization and the like, is more and more widely applied, the demand is increased year by year, and the market prospect is wide.

At present, two production methods of a rotary kiln and a vertical kiln are adopted for active lime in China, the lime produced by the rotary kiln has good activity and large market demand; in view of the reasons, partial equipment and facilities of the existing cement clinker line are utilized to improve the existing rotary kiln cement line into a lime line, an adding material metering device, a lifting machine and a lime preheater are required to be added at the tail part of the rotary kiln, and meanwhile, the existing grate cooler is improved, so that the roasting process of the active lime in the rotary kiln is provided.

[ summary of the invention ]

In view of the above, the present invention aims to provide a roasting process for active lime in a rotary kiln, wherein the production process for the active lime does not add and generate any harmful substances from the used raw materials to the process, the lime with high activity is prepared by adding additives and a scientific and reasonable production process, and simultaneously, the lime can maintain high activity for a long time, and the preparation process is simple, has high operability, is green and environment-friendly, and has great social value and economic benefit.

In order to solve the technical problems, the invention adopts the following technical scheme:

a roasting process of active lime in a rotary kiln comprises the following steps:

(1) pretreatment of raw materials: washing limestone raw materials to remove impurities, drying, and crushing the limestone raw materials into crushed stones with the diameter of 8-10mm by a hammer crusher, wherein the crushing frequency of the hammer crusher is 380 plus 420T/h;

(2) preparation of the additive: uniformly mixing modifier, dispersant and chlorate according to the mass ratio of 3-4:1-2: 5-7;

(3) preparation of limestone powder: mixing the crushed stone obtained in the step (1) with the additive obtained in the step (3), and then inputting the mixture into a vertical mill for grinding and sieving to prepare a calcined raw material with the particle size of 5-7 mm;

(4) primary calcination: supplying coal gas to a decomposer outside the kiln by a coal gas generator to carry out primary calcination on the calcined raw material and carry out partial decomposition in the decomposer outside the kiln, wherein the temperature is set at 650-850 ℃;

(5) secondary calcination: feeding the powder decomposed by the decomposer into a rotary kiln with an inner cavity of the kiln body provided with a heat insulation layer with the thickness of 15-40mm and a wall refractory brick of the inner cavity of the kiln body provided with a bulge for curing and calcining, wherein the temperature is set at 900-;

(6) discharging: discharging from a discharge port of the rotary kiln, and cooling to 180-220 ℃ to obtain the active lime finished product, wherein the cooling medium adopts brine ice.

In the invention, furthermore, the limestone raw material adopted in the step (1) is high-quality lime with calcium content higher than 53%.

In the present invention, further, the step (4) is performed by performing the following steps before performing the primary calcination: the calcining raw material is sent into the rotary kiln body, bituminous coal is adopted for presintering, the presintering temperature is 650-750 ℃, the presintering time is 160-180min, the rotating speed of the rotary kiln is 2-3r/min, and meanwhile, sufficient oxygen in the kiln body is ensured.

In the invention, further, the dispersant in the step (3) is composed of the following raw materials in parts by weight: 28-42 parts of organic polycarboxylate dispersant, 12-20 parts of inorganic polyphosphate dispersant, 5-10 parts of talcum powder, 3-8 parts of flatting agent and 8-16 parts of butyl acetate.

In the invention, the modifying agent in the step (3) is composed of the following raw materials in parts by weight: 35-55 parts of chromium compound, 75-95 parts of propanol, 3-8 parts of stearic acid, 12-18 parts of bran powder, 75-95 parts of carrier, 7-11 parts of tea oil and 5-6 parts of alkali liquor.

In the present invention, further, the carrier is calcium oxide or calcium silicate.

In the invention, further, the alkali liquor is potassium hydroxide solution or sodium hydroxide solution.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. the roasting process of the active lime in the rotary kiln does not add and generate any harmful substance from the used raw materials to the process, the raw materials adopt limestone with high calcium content as the raw materials, and the granularity of the raw materials is crushed to be between 5 and 7mm, so that the limestone is quickly decomposed in the kiln, the heat loss is reduced, the raw burning is avoided, the granularity is too small, the pores among the materials are small, the heat transfer is not uniform, and the local overburning is generated; through production contrast and by adopting a proper particle size ratio, the retention time of materials can be effectively shortened, the loss of a material layer is reduced, the heat conduction condition is improved, and the activity of lime is improved. Firstly, performing powdering treatment on raw limestone to ensure that the raw material to be fed into a preheater does not appear in the shape of lump stone any more; in the subsequent primary calcining and slaking calcining stages, the complete slaking result generated by the continuous calcining process consisting of the preheater, the outside-kiln decomposer and the rotary kiln is incomparable with the traditional equipment and the production process, so that the calcining effect is improved in an optimized manner, the content of sulfur in lime can be effectively reduced, the power consumption is further reduced, the activity of limestone is improved, and the high-efficiency active lime is obtained.

2. In the production process of the active lime, the modifying agent is added into the lime powder, the modifying agent consists of a chromium compound, propanol, stearic acid, bran powder, a carrier, tea oil and alkali liquor, the tea oil belongs to natural vegetable oil, has good environmental protection performance and extremely strong intermiscibility, and can promote the mutual fusion of the raw materials of all the components; the wheat bran which is ground into powder is added, the wheat bran contains a large amount of lignin, so the wheat bran has strong adsorbability and can be used as a deodorant, the modifier is added, a film is formed on the surface of the lime powder particles by a physical method to reduce the surface energy of the lime powder particles, and the film solves the problems of easy deliquescence and poor liquidity of the common lime powder when meeting water by virtue of hydrophobicity and smoothness of the film, so that the lime powder has the characteristics of waterproof performance and easy flowing, and can keep high activity for a long time, thereby prolonging the service time of the active lime powder, improving the use efficiency of the active lime powder and saving resources. The active lime powder added with the invention has high activity, strong water resistance and good fluidity.

3. In the production process of the active lime, the dispersing agent is added into the lime powder, and the organic polycarboxylate dispersing agent and the inorganic polyphosphate dispersing agent are used as main raw materials, so that the fineness and viscosity of limestone slurry can be reduced, the uniformity, stability and fluidity of the slurry are improved, the adsorptivity and stability of the lime can be improved by adding the talcum powder, and the ageing resistance is improved by adding the leveling agent; the added butyl acetate can provide good flow resistance, and can be used as an organic solvent to better fuse the raw materials of each component together, so that the performance and the function of each raw material can be better exerted.

[ detailed description ] embodiments

The following examples may help one skilled in the art to more fully understand the present invention, but are not intended to limit the invention in any way.

Example 1

The roasting process of the active lime in the rotary kiln provided by the embodiment comprises the following steps:

(1) pretreatment of raw materials: washing a high-quality limestone raw material with calcium content higher than 53% with water to remove impurities, drying, and crushing by a hammer crusher until the limestone raw material is crushed into crushed stone with the diameter of 8mm, wherein the crushing frequency of the hammer crusher is 380T/h;

(2) preparation of the additive: uniformly mixing a modifier, a dispersant and chlorate according to a mass ratio of 3:1: 5;

(3) preparation of limestone powder: mixing the crushed stone obtained in the step (1) with the additive obtained in the step (3), and then inputting the mixture into a vertical mill for grinding and sieving to prepare a calcined raw material with the particle size of 5 mm; the dispersing agent is prepared from the following raw materials in parts by weight: 28 parts of organic polycarboxylate dispersant, 12 parts of inorganic polyphosphate dispersant, 5 parts of talcum powder, 3 parts of flatting agent and 8 parts of butyl acetate; the modifier consists of the following raw materials in parts by weight: 35 parts of chromium compound, 75 parts of propanol, 3 parts of stearic acid, 12 parts of bran powder, 75 parts of carrier, 7 parts of tea oil and 5 parts of alkali liquor; wherein the carrier is calcium oxide or calcium silicate; the alkali solution is potassium hydroxide solution or sodium hydroxide solution.

(4) Primary calcination: feeding the calcined raw material into a rotary kiln body, presintering by adopting bituminous coal, wherein the presintering temperature is 650 ℃, the presintering time is 160min, the rotating speed of the rotary kiln is 2r/min, and simultaneously ensuring sufficient oxygen in the kiln body, then supplying coal gas to a decomposer outside the kiln by a coal gas generator to carry out primary calcination on the calcined raw material and carrying out partial decomposition in the decomposer outside the kiln, wherein the temperature is set at 650 ℃;

(5) secondary calcination: feeding the powder decomposed by the decomposer into a rotary kiln with an inner cavity of the kiln body provided with a heat insulation layer with the thickness of 15mm and a wall refractory brick of the inner cavity of the kiln body provided with a bulge for curing and calcining, wherein the temperature is set at 900 ℃;

(6) discharging: discharging from a discharge port of the rotary kiln, and cooling to 180 ℃ to obtain a finished product of the active lime, wherein the cooling medium adopts brine ice.

Example 2

(1) pretreatment of raw materials: washing a high-quality limestone raw material with calcium content higher than 53% to remove impurities, drying, and crushing by a hammer crusher to obtain crushed stone with the diameter of 9mm, wherein the crushing frequency of the hammer crusher is 400T/h;

(2) preparation of the additive: uniformly mixing a modifier, a dispersant and chlorate according to a mass ratio of 3:2: 6;

(3) preparation of limestone powder: mixing the crushed stone obtained in the step (1) with the additive obtained in the step (3), and then inputting the mixture into a vertical mill for grinding and sieving to prepare a calcined raw material with the particle size of 6 mm; the dispersing agent is prepared from the following raw materials in parts by weight: 35 parts of organic polycarboxylate dispersant, 16 parts of inorganic polyphosphate dispersant, 7 parts of talcum powder, 6 parts of flatting agent and 12 parts of butyl acetate; the modifier consists of the following raw materials in parts by weight: 45 parts of chromium compound, 85 parts of propanol, 6 parts of stearic acid, 15 parts of bran powder, 85 parts of carrier, 9 parts of tea oil and 5 parts of alkali liquor; wherein the carrier is calcium oxide or calcium silicate; the alkali solution is potassium hydroxide solution or sodium hydroxide solution.

(4) Primary calcination: feeding the calcined raw material into a rotary kiln body, presintering by adopting bituminous coal, wherein the presintering temperature is 700 ℃, the presintering time is 170min, the rotating speed of the rotary kiln is 2.5r/min, simultaneously ensuring sufficient oxygen in the kiln body, then supplying coal gas to a decomposer outside the kiln by a coal gas generator to carry out primary calcination on the calcined raw material and carrying out partial decomposition in the decomposer outside the kiln, and the temperature is set to 750 ℃;

(5) secondary calcination: feeding the powder decomposed by the decomposer into a rotary kiln with an inner cavity of the kiln body provided with a heat insulation layer with the thickness of 26mm and a wall refractory brick of the inner cavity of the kiln body provided with a bulge for curing and calcining, wherein the temperature is set to 1150 ℃;

(6) discharging: discharging from a discharge port of the rotary kiln, and cooling to 200 ℃ to obtain a finished product of the active lime, wherein the cooling medium adopts brine ice.

Example 3

(1) pretreatment of raw materials: washing a high-quality limestone raw material with calcium content higher than 53% to remove impurities, drying, and crushing by a hammer crusher until the limestone raw material is crushed into crushed stone with the diameter of 10mm, wherein the crushing frequency of the hammer crusher is 420T/h;

(2) preparation of the additive: uniformly mixing a modifier, a dispersant and chlorate according to a mass ratio of 4:2: 7;

(3) preparation of limestone powder: mixing the crushed stone obtained in the step (1) with the additive obtained in the step (3), and then inputting the mixture into a vertical mill for grinding and sieving to prepare a calcined raw material with the particle size of 7 mm; the dispersing agent is prepared from the following raw materials in parts by weight: 42 parts of organic polycarboxylate dispersant, 20 parts of inorganic polyphosphate dispersant, 10 parts of talcum powder, 8 parts of flatting agent and 16 parts of butyl acetate; the modifier consists of the following raw materials in parts by weight: 55 parts of chromium compound, 95 parts of propanol, 8 parts of stearic acid, 18 parts of bran powder, 95 parts of carrier, 11 parts of tea oil and 6 parts of alkali liquor; wherein the carrier is calcium oxide or calcium silicate; the alkali solution is potassium hydroxide solution or sodium hydroxide solution.

(4) Primary calcination: feeding the calcined raw material into a rotary kiln body, presintering by adopting bituminous coal at the presintering temperature of 750 ℃ for 180min, and ensuring that the rotary kiln rotates at the speed of 3r/min and oxygen in the kiln body is sufficient, and then supplying coal gas to a decomposer outside the kiln by a coal gas generator to perform primary calcination on the calcined raw material and perform partial decomposition in the decomposer outside the kiln, wherein the temperature is set at 850 ℃;

(5) secondary calcination: feeding the powder decomposed by the decomposer into a rotary kiln with an inner cavity of the kiln body provided with a heat insulation layer with the thickness of 40mm and a wall refractory brick of the inner cavity of the kiln body provided with a bulge for curing and calcining, wherein the temperature is set at 1200 ℃;

(6) discharging: discharging from a discharge port of the rotary kiln, and cooling to 220 ℃ to obtain a finished product of the active lime, wherein the cooling medium adopts brine ice.

Comparative example

A production process of active lime comprises the following steps:

(1) preparing limestone fine powder: crushing limestone into powder, and sieving the powder by a 100-mesh sieve to obtain limestone fine powder for later use;

(2) preparation of the additive: respectively taking coal powder and sodium silicate, and uniformly mixing the coal powder and the sodium silicate, wherein the ash content of the coal powder is less than 6 wt%, the granularity is 200 meshes, and the mass ratio of the coal powder to the sodium silicate is 10:2: 5;

(3) mixing materials: uniformly stirring and mixing the limestone fine powder prepared in the step (1) and the additive prepared in the step (2) to obtain a mixture, wherein the mass ratio of the limestone fine powder to the additive is 10: 0.8;

(4) and (3) calcining: and (4) feeding the mixture obtained in the step (3) into a kiln to be calcined at 1160 ℃ for 1.6 h.

Effect verification

In order to illustrate the value of the present invention more clearly, the physical and chemical properties and performance of the lime prepared in the above examples 1-3 and comparative examples were tested by using DL/T1483-2015, and the results are shown in the following table:

item	Example 1	Example 2	Example 3	Comparative example
					CaO(wt.％)	92.87	93.25	92.96	85.32
C(wt.％)	0.02	0.01	0.02	0.65
					S(wt.％)	0.02	0.03	0.03	0.23
Degree of activity (mL)	506	510	509	410

As can be seen from the table above, the indexes of the examples 1 to 3 are superior to those of the comparative examples, and the invention uses a plurality of additives and limits the mixture ratio thereof, thereby further reducing the power consumption, improving the activity degree of the lime and obtaining the lime with high activity.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. The roasting process of the active lime in the rotary kiln is characterized by comprising the following steps:

(3) preparation of limestone powder: mixing the crushed stone obtained in the step (1) with the additive obtained in the step (2), and then inputting the mixture into a vertical mill for grinding and sieving to prepare a calcined raw material with the particle size of 5-7 mm;

(6) discharging: discharging from a discharge port of the rotary kiln, and cooling to 180-220 ℃ to obtain a finished product of the active lime, wherein the cooling medium adopts brine ice;

the dispersing agent in the step (2) is prepared from the following raw materials in parts by weight: 28-42 parts of organic polycarboxylate dispersant, 12-20 parts of inorganic polyphosphate dispersant, 5-10 parts of talcum powder, 3-8 parts of flatting agent and 8-16 parts of butyl acetate;

the modifying agent in the step (2) is prepared from the following raw materials in parts by weight: 35-55 parts of chromium compound, 75-95 parts of propanol, 3-8 parts of stearic acid, 12-18 parts of bran powder, 75-95 parts of carrier, 7-11 parts of tea oil and 5-6 parts of alkali liquor;

the carrier is calcium oxide or calcium silicate.

2. The roasting process of active lime in a rotary kiln according to claim 1, wherein the limestone raw material adopted in the step (1) is high-quality lime with calcium content higher than 53%.

3. The roasting process of active lime in a rotary kiln as claimed in claim 1, wherein the step (4) is performed by the following steps before the primary roasting: the calcining raw material is sent into the rotary kiln body, bituminous coal is adopted for presintering, the presintering temperature is 650-750 ℃, the presintering time is 160-180min, the rotating speed of the rotary kiln is 2-3r/min, and meanwhile, sufficient oxygen in the kiln body is ensured.

4. The roasting process of active lime in a rotary kiln as claimed in claim 1, wherein the alkali liquor is potassium hydroxide solution or sodium hydroxide solution.