Mobile Crushing at Cement Plants in the Philippines
What are the major processes of cement plants?
- Mixing and preheating
- Cooling and final grinding
Cement is one of the most important building materials used to date. It is an extremely effective binding agent that sets and hardens in place in order to literally stick building materials such as stones, bricks, and tiles together. Road rollers are usually used when these cement mixtures are needed for parking lots or any kind of flat surface—just to make sure that the cement sets evenly.
That being said, cement refers to a very fine powdery substance that is mainly made of limestone, sand, clay, and iron ore. It would often include more materials such as shells, chalk, marble, shale, slag, and slate—all of which are mixed into the whole cement mixture.
This interesting composition of cement is not easy to make—in fact, the entire cement making process is rather simple but needs specialized equipment so that everything can be done smoothly. Let’s take a look at the typical cement production process.
As with most building materials, the process of making them starts with extraction. In this case, most of the materials mentioned above, particularly limestone, sand, iron, and shale are extracted straight from the earth.
Often, extraction would also include the act of accumulating demolition debris. All of these raw and recycled materials are gathered and transported to designated sites for the next step of the process.
Cement plants can do the crushing two ways. They can transport all of them onto the cement site itself where an immobile crusher is installed and integrated into the whole system. Or they have a mobile crusher ready at the quarry itself.
The difference between the two is mainly in the transportation of materials. If the crushing plant is in the main cement plant, then large chunks of rock and earth will be transported through kilometers. If the crushing is done on site, however, you will only need to transport smaller particles, letting you bring more on the journey.
These small, coarse particles will be sent to mills to be further ground into a finer powder. Afterward, they will be analyzed to distinguish different materials from the other. Bear in mind that cement is made with a mixture of raw materials in particular percentages depending on the company making them. There are many different cement mixes—all of which have their own advantages and disadvantages.
Mixing and Preheating
Once the powders are mixed and blended, they are preheated to approximately 900 degrees Celsius. This is typically done using the hot gases from a kiln. Preheating these powders is important because it burns off more impurities. With no impurities, cement mixes become more efficient when serving as a binding agent. It sets evenly, the binding that happens is stronger and there will be little to no pores within the mixture itself.
After burning off the impurities, the materials are let to cool for a while and then burned again within a larger, rotating kiln at around 1500 degrees Celsius. The high temperature facilitated de-carbonation where CO2 is driven out of the limestone. The resulting melted, slightly fused substance is known as clinker.
Modern-day kilns are big and efficient enough to produce around 6000 tons of clinker in a day.
Cooling and Final Grinding
The clinker itself is left to rest and cool after the intense heat. Cement cooling is an incredibly important step as it reduces the chances of gypsum dehydration and the formation of lumps in the clinker. These all result in the lowering of the overall quality of the final cement. In most cases, customers also demand that the initial temperature of the cement mixtures are lower in order to minimize the evaporation effect on the final mix. This further helps them improve quality control and achieve more consistent concrete strengthening.
Before going to the customers, however, the clinker is put into a tube or ball mill. The ball mill is basically a large rotating drum filled with steel balls of different sizes. The size of the balls depends on the desired fineness of the cement powder. They basically crush and grind the clinker into the desired fineness.
One common practice is the addition of gypsum during the whole grinding process. Its presence provides a means to control the setting of the cement. Once the cement is ground into the desired feel, the cement is bagged and transported for distribution or concrete production.
Some cement plants make use of mobile crushers in their quarries. Aside from that, most of the equipment used in the cement production process is specialized for them. That being said, they still need the basic material handling equipment in the transport of raw materials all over.
Cement plants are great industrial areas that facilitate the manufacturing of one of the most important building materials. The process itself takes a long time and needs a lot of analysis and attention—all for the production of the most practical binding unit for buildings, cement.