Seeking cement production process flow

1. cement: cement is a kind of hydraulic cementing material, which can harden in air and water, and can firmly bond sand and gravel together. Generally speaking, the cement industry produces Portland cement, which is a fine, usually gray calcium powder? (? From limestone? )、? Silicate, aluminate? (? Clay? )? And ferrite.

From the firing kiln, there are vertical kiln (including mechanical kiln) and rotary kiln (rotary kiln). The forms of raw materials entering the kiln are dry method and wet method. If the raw material is slurry, it is wet. ? Generally speaking, it is based on how many tons per day.

(1) cement is divided into:?

1, general cement,? Cement commonly used in general civil engineering. General cement mainly refers to six types of cement specified in GB 175- 1999, GB 1344- 1999 and GB 12958- 1999, namely portland cement and ordinary portland cement. ?

2. Special cement and special cement. For example: G-class oil well cement and road portland cement.

3. Characteristic cement, a kind of cement with outstanding performance. Such as: quick-hardening portland cement, low-heat slag portland cement and expanded sulphoaluminate cement.

(2) Cement is divided into:

(1) Portland cement, commonly known as Portland cement abroad;

(2) Aluminate cement;

(3)? Sulphoaluminate cement;

(4) iron aluminate cement;

(5) Fluoroaluminate cement;

(6) Cement with active substances such as volcanic ash or potential hydraulic materials as the main component.

(3) The main technical characteristics of cement indicated as required in cement naming are as follows:

( 1)? Fast hardening: divided into fast hardening and fast hardening; ?

(2)? Hydration heat: divided into two categories: moderate heat and low heat;

(3)? Sulfate resistance: divided into two categories: moderate sulfate resistance and high sulfate resistance; ?

(4)? Expansibility: it is divided into two categories: expansion and self-stress;

(5)? High temperature resistance: the high temperature resistance of aluminate cement is graded according to the content of alumina in cement. ?

(4) The general principles of cement naming:

1. The naming of cement is based on the main hydraulic minerals, mixed materials, uses and main characteristics of cement, so as to be concise and accurate. Abbreviations are allowed when the name is too long.

2. General cement is named after the name of the main hydraulic minerals of cement and the name of the admixture or other appropriate names. ?

3. Special cement is named after its special use, and can be labeled with different models. ?

4. Characteristic cement is named after the main hydraulic minerals of cement, which can be named according to different models or mixed materials. ?

5. Cement with pozzolan or potential hydraulic materials and other active substances as the main components shall be named after the active substance with the name of the main component, or it may be named after the characteristic name, such as persulfate cement and lime pozzolan cement.

6. People who know a little about cement production technology will talk about "two grinding and one burning" when talking about cement production, namely: raw material preparation (first grinding), clinker calcination (first burning) and cement grinding (second grinding). In silicate? In the cement plant, cement production has the following main stages.

Second, the preparation of raw materials?

(1) Limestone is the main raw material for producing cement. Every ton of clinker needs about 1.3 tons of limestone, and more than 80% of the raw materials are limestone. Most factories are located near limestone quarries to minimize transportation costs.

1, do you use blasting or cutting machine for raw materials? (? Limestone, shale Silica and pyrite? )? Extraction of. ? Raw materials are sent to a crusher, where they are crushed or hammered into pieces.

2. Crushed limestone and other raw materials are usually covered and stored to prevent them from being affected by the external environment, and at the same time, dust can be reduced to a minimum. ?

3. In most cases, quarries and cement plants will need separate or separate power supply equipment. ? Limestone is the most used raw material in cement production. After mining, the particle size is large and the hardness is high, so the crushing of limestone plays an important role in the crushing of materials in cement plants.

(2) raw materials are crushed and pre-homogenized

(1) In the process of producing crushed cement, most raw materials are crushed, such as limestone, clay, iron ore and coal. Limestone is the most used raw material in cement production. After mining, the particle size is large and the hardness is high, so the crushing of limestone plays an important role in the crushing of materials in cement plants. ?

Raw materials are transported by dump trucks and dumped into garbage dumps, and then sent to crushers by plate feeders for crushing. The crushed raw fuel is sent to the pre-homogenization field by the belt conveyor.

(2) Pre-homogenization of raw materials Pre-homogenization technology is to realize the initial homogenization of raw materials by using scientific stacking technology in the process of raw material storage and retrieval, so that the raw material storage yard has both storage and homogenization functions. ?

The crushed raw materials are pre-homogenized by a stacker and stacked in layers, and then taken by a scraper reclaimer. The raw materials taken out are sent to raw material batching station and other places by belt conveyor.

(3) Main equipment

1, limestone plate feeder? Layout position? Located in limestone crushing workshop? Use? Way? Used for limestone feeding?

2. Limestone crusher? Use? Way? Used to crush limestone? Layout position? Limestone crushing workshop in the factory? Broken type? Single hammer (PCF20. 18)?

3, limestone mixed stacker reclaimer

Thirdly, raw meal grinding.

1, raw meal preparation?

In the process of cement production, every 65,438+0 tons of portland cement is produced, at least 3 tons of materials (including various raw materials, fuels, clinker, mixtures and gypsum) are ground. According to statistics, the grinding operation of dry cement production line consumes more than 60% of the power of the whole plant, of which raw meal grinding accounts for more than 30%, pulverized coal grinding accounts for about 3%, and cement grinding accounts for about 40%. Therefore, it is of great significance to reasonably select grinding equipment and process flow, optimize process parameters and correctly operate and control the operating system to ensure product quality and reduce energy consumption. ?

At this stage, vertical mill and ball mill are used. The former uses the pressure leaking from the drum? Crushing the passing material, which grinds the material with steel balls.

(1) The production process of the old ball mill: four kinds of raw materials in the raw material batching bin are transported to the grinding head by seven quantitative feeders and belt conveyors according to the set raw material ratio, and then enter the feeding bin of the roller press through the gate. After the materials are pre-pulverized by a roller press, they are sent to a powder separator by a crusher, and the selected coarse powder enters a mill for grinding. The ground materials are sent to the classifier (cyclone) through the elevator, and the qualified products selected by the classifier (cyclone) are sent out.

When the roller press fails, the material can be directly sent to the mill for grinding through the control of the gate. The ground raw materials enter the classifier from the upper part and are separated by the classifier. The coarse powder is discharged from the lower part, and the qualified fine powder is brought into the cyclone by the ascending airflow. The gas material is separated in the cyclone separator, the dusty waste gas is pumped from the upper part to the dust collector, and the finished product is discharged from the lower part to the raw material bin. Although the system works continuously, the production efficiency of the system will be affected at this time.

Raw meal is ground by waste hot gas discharged from sintering system. In the process of grinding the material, the material is simultaneously dried. The dusty waste gas produced by grinding will enter the classifier together with another hot waste gas from the kiln tail. Dust-bearing waste gas discharged from the classifier is sent to the bag dust collector and discharged into the atmosphere after purification.

(2) The working principle of the classifier:

Four cyclones are distributed around the middle body of the classifier. The ground raw materials enter the classifier from the upper part and are separated by the classifier, and the coarse powder is discharged from the lower part, and the qualified fine powder is brought into the cyclone by the updraft. The gas material is separated in the cyclone separator, and the dusty waste gas is pumped from the upper part to the dust collector, and the finished product is discharged from the lower part to the raw material bin for firing.

(3) The working principle of the new vertical mill for raw meal: (with its own classifier)?

1, raw meal grinding adopts vertical mill. This mill combines the advantages of grinding and drying, so it has high drying and grinding ability. The inlet of the mill adopts a three-way gate air supply device.

2. The mixed material falls into the center of the grinding disc of the vertical mill from the feed inlet, and at the same time, the waste gas at the end of the kiln at about 300℃ enters the mill from the air inlet of the vertical mill. Under the action of centrifugal force, the material moves to the edge of the grinding disc and is crushed by the grinding roller when passing through the annular groove on the grinding disc. The crushed materials are picked up by the high-speed airflow around the edge of the grinding disc, and the large particles directly fall on the grinding disc and are crushed again. When the material in the airflow passes through the separator, it is crushed.

3. Qualified fine powder is carried into the cyclone by the ascending airflow. The gas material is separated in the cyclone separator, and the dusty waste gas is pumped from the upper part to the dust collector, and the finished product is discharged from the lower part to the raw material bin for firing. Part of the coarse powder of the raw meal mill can't be taken away by the airflow when it passes through the wind ring, but is scraped out by the scraper, forming an external circulating material. The maximum circulation of this part is 40t.

4. The raw material ball mill is mainly used for grinding finished products and raw materials in cement plants, and is also suitable for grinding various ores and other grindable materials in metallurgical, chemical and electric power enterprises. It can be used for open flow grinding, and can also be used for circulating loop grinding with classifier. ?

5. The raw material ball mill has the characteristics of strong adaptability to materials, continuous production, large crushing ratio and easy adjustment of grinding product fineness. It can be produced by wet method or by grinding and drying simultaneously. ?

6. Compared with the ball mill, the vertical mill has the following characteristics:

7, high grinding efficiency; High drying capacity; The particle size of the grinding material is large, and the secondary crushing can be omitted in large and medium-sized vertical grinding; The chemical composition of the product is stable; Uniform particle size and product size, which is beneficial to calcination; The process flow is simple; Low noise, less dust and clean operating environment; ? Low metal loss and high utilization rate; ? Use economy.

(4) raw meal homogenization?

1. In the process of new dry cement production, stabilizing the composition of into the pit raw meal is the premise of stabilizing the thermal system of clinker burning, and the raw meal homogenization system plays the final role in stabilizing the composition of into the pit raw meal.

2. The production line is equipped with a continuous raw material homogenizing bin to store and homogenize raw materials. After the raw materials in the silo are alternately inflated in different areas, they are discharged from the peripheral annular area to the mixing chamber, and the raw materials are inflated and stirred evenly in the mixing chamber. After being metered, the homogenized raw meal powder passes through a gas conveying chute and a bucket elevator, and then enters two feed inlets of a double series preheater through a material distributing valve and a lock valve respectively. ?

(5) The principle of raw meal homogenization: The "funnel effect" is generated by air stirring and gravity, so that when the raw meal powder is discharged downward, as many layers as possible are cut and fully mixed. Using different fluidization winds, the parallel material surfaces in the silo are fluidized and expanded into different sizes, some areas are discharged and some areas are fluidized, so that the material surfaces in the silo are inclined and radially homogenized.

(6) Main equipment

1, roller mill

2. Bag filter at kiln end?

3. Exhaust fan of kiln tail bag dust collector? Use? Used for waste gas treatment of kiln tail and raw meal grinding system? Layout position? After collecting dust in the kiln tail bag? Working air temperature? Normal:? 80~ 150℃? Limit temperature: 200℃?

4. High temperature fan at kiln end? Use? Used to extract waste gas from preheater? Layout position? Behind the preheater and behind the humidifying tower? Working air temperature? Normal temperature: 320 ~ 350℃; ? Limit temperature: 450℃; ? Fan blades should be made of high-quality wear-resistant materials to ensure the long life of rotor blades.

5. Raw material mill circulating fan? Use? Ventilation for raw material grinding system? Layout position? What is the working air temperature after the raw material mill combined with cyclone? Normal: 90~ 100℃? Limit temperature (short time): 250℃? Fan blades should be made of high-quality wear-resistant materials to ensure the long life of rotor blades.

Fourth, clinker burning?

1. The raw meal powder entering the preheater is heat-exchanged in the preheater, pre-decomposed in the calciner, then enters the rotary kiln through the discharge pipe of the five-stage cyclone, and then sintered at high temperature in the rotary kiln, and then falls into the grate cooler through the kiln mouth for cooling, and then the clinker is cooled to the ambient temperature of +65℃, and then transported to the clinker warehouse and the yellow material warehouse through the zipper. ?

2. Ventilation of kiln head is mainly composed of primary air (including air for conveying pulverized coal and burning pulverized coal), secondary air (high temperature air directly entering the kiln from grate cooler with gas temperature of 950 ~ 1 100℃) and tertiary air (high temperature air directly entering the calciner from grate cooler through tertiary air duct).

3. The air volume required for grate cooler cooling is provided by 7 high-pressure and medium-pressure fans. In addition to supplying secondary air and tertiary air, part of the cooling air provides heat for the coal mill (flue gas temperature is 400℃), and the excess waste gas is collected by the multi-tube cyclone and discharged into the atmosphere. ?

4. The exhaust gas at the kiln tail with a temperature of about 350 degrees is pumped from the top of the preheater by a high-temperature fan, and the air is diverted at a suitable place in the outlet pipeline of the fan, one part of which goes to the coal mill to dry the pulverized coal, and the other part goes to the raw meal mill to dry the raw meal. Other gases enter the humidifying tower, and water is sprayed in the tower to cool down. After the dust is preliminarily precipitated, the gas is discharged. The dusty gas discharged from the combined raw meal mill enters the bag dust collector and is discharged into the atmosphere after purification.