Raw meal workshop: limestone crusher (hammer crusher, jaw crusher, etc.), stacker and reclaimer for limestone pre-homogenization, raw meal mill
Burning workshop: coal pre-homogenization equipment, coal mill, rotor scale, preheater, rotary kiln, cooler, etc.
Cement workshop: cement blending, roller press, cement mill, packaging machine, etc.
There are also various metering belts, belt conveyors, fans, etc.
Process flow
1. Crushing and pre-homogenization
(1) Crushing During the cement production process, most of the raw materials must be crushed, such as limestone, clay, iron ore and coal. Limestone is a large amount of raw material for cement production. After mining, it has a larger particle size and higher hardness. Therefore, limestone is a large amount of raw material for cement production. After mining, it has a larger particle size and higher hardness. Therefore, the crushing of limestone is in the cement plant. Occupies a relatively important position in the crushing of materials.
The crushing process is more economical and convenient than the grinding process. It is very important to select crushing equipment and grinding equipment reasonably. Before the material enters the grinding equipment, crush large pieces of material to a fine and uniform particle size as much as possible to reduce the load of the grinding equipment and increase the output of the milling machine. After the materials are crushed, the separation phenomenon of materials of different sizes during transportation and storage can be reduced, and raw materials with uniform composition can be obtained, and the accuracy of ingredients can be improved.
(2) Raw material pre-homogenization Pre-homogenization technology is to use scientific stacking and reclaiming technology to realize the initial homogenization of raw materials during the storage and retrieval of raw materials, so that the raw material storage yard has the functions of storage and homogenization at the same time.
The basic principle of raw material pre-homogenization is that when the materials are stacked, the stacker continuously stacks the incoming raw materials in a certain manner into as many layers as possible that are parallel to each other, overlap each other and have the same thickness. When taking the material, in the direction perpendicular to the material layer, try to cut all the material layers at the same time as much as possible, and cut them in sequence until they are finished, that is, "flat and straight take".
significance:
(1) Homogenize the raw material composition to reduce quality fluctuations, so as to facilitate the production of higher quality clinker and stabilize the production of the firing system.
(2) Expand the utilization of mine resources, improve mining efficiency, and expand the covering and interlayer of the mine to a large extent, so that no or less waste rock will be produced in the process of mining.
(3) The quality and control requirements of mining can be relaxed, and the mining cost of the mine can be reduced.
(4) Strong adaptability to sticky and wet materials.
(5) To provide the factory with long-term stable raw materials, it is also possible to batch raw materials of different components in the yard to make it a pre-batch yard, creating conditions for stable production and improving equipment operation rate.
(6) High degree of automation.
2. Raw meal preparation
In the cement production process, at least 3 tons of materials (including various raw materials, fuels, clinkers, mixtures, and gypsum) must be ground for every 1 ton of Portland cement produced. According to statistics, the grinding operation of dry-process cement production lines needs to consume Power accounts for more than 60% of the power of the whole plant, of which raw meal grinding accounts for more than 30%, coal grinding accounts for about 3%, and cement grinding accounts for about 40%. Therefore, reasonable selection of grinding equipment and process flow, optimization of process parameters, correct operation, and control of the operating system are of great significance for ensuring product quality and reducing energy consumption.
Working principle:
The motor drives the grinding disc to rotate through the deceleration device, and the material falls into the middle of the grinding disc through the feeder through the lock air feeding device, and is thrown to the edge of the grinding disc under the action of centrifugal force to be ground by the grinding roller, and the crushed material is removed from the grinding disc. The edge overflows from the nozzle and is brought to dry by the high-speed upward hot airflow from the nozzle. According to the different airflow speed, part of the material is carried by the airflow into the effective powder separator. The coarse powder is separated and returned to the grinding plate for re-grinding; The powder exits the mill along with the airflow and is collected in the dust collection device of the system to become the product. The coarse particles that have not been carried by the hot air flow overflow the grinding disc and are fed into the powder concentrator by the outer circulating bucket elevator. The coarse particles fall back to the grinding disc and are squeezed again for grinding.
3. Homogenization of raw meal
In the new dry process cement production process, stabilizing the composition of raw meal into the pit is the prerequisite for stabilizing the thermal system of clinker firing, and the raw meal homogenization system plays a role in stabilizing the composition of raw meal into the pit.
Homogenization principle:
Adopt air stirring and gravity to produce the "funnel effect", so that when the raw meal powder is discharged downward, it is possible to cut multiple layers of material and mix it fully. The use of different fluidizing air causes the parallel material surfaces in the silo to have different sizes of fluidized expansion, some areas are unloaded, and some areas are fluidized, so that the material surface in the silo is tilted for radial mixing and homogenization.
4. Preheating and decomposition
The preheating and partial decomposition of the raw meal are completed by the preheater, replacing part of the functions of the rotary kiln, so as to shorten the length of the kiln, and at the same time make the kiln feed the heat exchange process in a stacked state, and move it to the preheater in a suspended state The process enables the raw meal to be fully mixed with the hot gas discharged from the kiln, increases the gas-material contact area, has a fast heat transfer rate and high heat exchange efficiency, and achieves the purpose of improving the production efficiency of the kiln system and reducing the heat consumption of clinker firing.
working principle:
The main function of Yongxian Machinery for the preheater is to make full use of the waste heat of the exhaust gas discharged from the rotary kiln and the decomposition furnace to heat the raw meal to preheat the raw meal and partially decompose the carbonate. In order to maximize the heat exchange efficiency between gas and solid, and realize the high output and low consumption of the whole calcining system, it has the three functions of uniform gas-solid dispersion, rapid heat exchange and effective separation.
(1) Material dispersion
80% of the heat exchange is carried out in the inlet pipe. The raw material fed into the preheater pipe is impacted by the high-speed updraft, the material turns and moves with the airflow, and is dispersed at the same time.
(2) Gas-solid separation
When the airflow carries the powder into the cyclone cylinder, it is forced to make a rotating flow in the annular space between the cyclone cylinder body and the inner cylinder (exhaust pipe), and move downward while rotating, from the cylinder to the cone. , Can extend to the end of the cone, and then rotate upwards to be discharged by the exhaust pipe.
(3) Pre-decomposition
The emergence of pre-decomposition technology is a technological leap in the cement calcination process. It is to add a decomposing furnace between the preheater and the rotary kiln, use the rising flue at the kiln tail, and set up a fuel injection device to make the exothermic process of fuel combustion and the endothermic process of the decomposition of carbonate of raw meal. The furnace is carried out quickly in a suspended state or a fluidized state, so that the decomposition rate of the raw meal into the kiln is increased to more than 90%. The carbonate decomposition task originally carried out in the rotary kiln is moved to the decomposition furnace; most of the fuel is added from the decomposition furnace, and a small part is added by the kiln head, which reduces the heat load of the calcining zone in the kiln and extends the lining. The material life is conducive to the large-scale production; because the fuel and the raw meal are evenly mixed, the fuel combustion heat is transferred to the material in time, so that the combustion, heat exchange and carbonate decomposition processes are optimized. Therefore, it has a series of excellent performance and characteristics such as effective and low consumption.
4. Burning of cement clinker
After the raw meal is preheated and pre-decomposed in the cyclone preheater, the next step is to enter the rotary kiln for clinker firing.
In the rotary kiln, the carbonate is further rapidly decomposed and a series of solid phase reactions occur to generate minerals such as,, and in the cement clinker. As the temperature of the material rises, minerals such as,, and will become liquid phase, and the dissolved in the liquid phase and react to produce a large amount of (clinker). After the clinker is fired, the temperature begins to drop. The cement clinker cooler cools the high-temperature clinker discharged from the rotary kiln to the temperature that the downstream transportation, storage and cement mill can withstand, and at the same time recovers the sensible heat of the high-temperature clinker to improve the thermal efficiency and clinker quality of the system.
5. Cement grinding
Cement grinding is a subsequent process in cement manufacturing, and it is also a process that consumes more electricity. Its main function is to grind cement clinker (and gelling agents, performance adjustment materials, etc.) to a suitable particle size (expressed in fineness, specific surface area, etc.) to form a certain particle gradation, increase its hydration area, and accelerate The hydration speed meets the requirements of cement paste coagulation and hardening.
6. Cement packaging
Cement leaves the factory with two shipping methods: bagged and bulk.