The cement industry is a capital-intensive and resource-intensive industry. With the convenience of international trade, overcapacity of production, rising investment, and other existing factors, many cement enterprises are suffering from increasing pressure to become more profitable. However, one of the main factors contributing to the success of an enterprise is the cost of production reduction. A sustainable cost reduction is also important for the development of cement factories. So how to minimize the production cost has become a crucial issue.
Dry method cement production is the most common cement manufacturing process in the cement industry. AGICO, as a cement plant equipment supplier in China, has been professional in building dry method cement plants for more than 20 years. Based on our experience and achievements, we believe that minimize the cement factory cost can be realized in each stage of cement production processes. For understanding, there is a cement manufacturing flow chart illustrated below:
Totally, if you want to reduce the plant cost, you can start firstly from three aspects:
- Site selection
- Cement equipment selection
- Cement factory layout
Next, we will further talk about the cost reduction method from three aspects mentioned above.
The site selection determines the construction and operating costs of a cement factory and is difficult to change once selected. Therefore, we should be careful about it, which requires multiple surveys and repeated comparisons. Generally, site selection should be based on the following principles:
- It’s better to have the most economical logistics transportation.
- The geology of the site is suitable to construct a cement plant.
- The factory site is away from environmentally sensitive areas and densely populated areas.
- It is in line with the master plan of the local government.
- Space should be large enough for further expansion.
- It is best to have a limestone mine near the site with a certain amount of reserves and meet the quality requirements.
All of these principles will help us to save unnecessary investment.
Cement Equipment Selection
As we all know, the cement manufacturing processes can be roughly divided into three stages: raw material preparation, clinker calcination, and cement grinding. To finish these processes, we need plenty of cement equipment. They will not only affect the cost in the early stage but also affect the energy consumption and production efficiency in the subsequent cement manufacturing.
Raw Material Crushing
Cement crushers we commonly used include:
- Cone crusher
- Jaw crusher
- Hammer crusher
- Impact crusher
In the early time, we usually adopt a two-stage crushing system with jaw crusher as the primary crusher and hammer crusher as the secondary crusher. Compared with two-stage crushing, the large capacity crusher applied in a single stage is more expensive. However, with the more mature technology appearing, large production capacity requirements, and increasing plant scale, we find that the use of single-stage crushers will lower investment to some extent, saving in power consumption and material handling. The single-stage hammer crusher and roller crusher are both good crusher models.
Raw Material Grinding & Cement Grinding
Cement ball mill and vertical roller mill are two grinders commonly used for cement grinding and raw material grinding. Compared with conventional ball mills, the vertical roller mill and the ball mill with high-efficiency separator are more energy-saving. Especially for the vertical roller mill, the motor only consumes about 7 – 8 kWh/ ton.
Clinker calcination can be divided into preheating, precalcining, burning, and cooling, four steps. It is the most important thermal energy consumption part of the cement plant. The preheater, precalciner, cement kiln, and cement cooler are the equipment we mostly used in this stage. With the development of technology, the transfer from the wet method to the dry method of cement manufacturing reduces thermal energy. Next is the upgraded adding of suspension preheater and precalciner. Their heat consumption is shown in the following table:
|Clinker Calcination Process||Heat Consumption Kcal/ kg|
|Wet Process||1300 – 1450|
|Dry process||1050 – 1250|
|1-stage cyclone preheater||900 -1050|
|2-stage cyclone preheater||900 – 950|
|4-stage cyclone preheater + precalciner||740 – 760|
|5-stage preheater + precalciner||715 – 730|
|6-stage preheater + precalciner||685 – 705|
Therefore, the 4-6 stage suspension preheater plus precalciner and cement kiln is the most energy-saving structure for clinker calcination. The production cost will be reduced accordingly.
Cement Factory Layout
Cement factory layout has a significant effect on the total energy consumption and civil engineering cost. So preparing a reasonable and effective layout design is crucial before establish a cement factory. In principle, the more compact the layout of cement plant, the lower the investment, as a compact layout design can reduce the land cost, shorten the distance of conveying equipment and material transfer distance, decrease the number of wires, cables, and water supply lines. Besides, an approach of good design would include:
- Make full use of the terrain to shorten the distance between the equipment and the workshops.
- Place the equipment in the open air as much as possible. This is the most direct way to reduce costs. Actually, in addition to considering the noise problem of the cement plant equipment, all the main or auxiliary machinery can be placed in the open air. This not only reduces the number of buildings but also convenient for equipment maintenance.
- Adopt the mechanical conveying instead of pneumatic conveying.
- Avoid the transfer towers for the belt conveyors.
- Set coal mill nearby the preheater, because preheater exhausted gases can be utilized inside the mill.
These aspects discussed above are of the most critical nature. As someone new to build a dry method cement factory, you can reduce the total investment by controlling these areas. Although the cost reduction is possible in other areas as well, it needs us to continuously explore and summarize.