Audit Procedures for Cement Production Tax. FLOW CHARTS OF MANUFACTURING PROCESS. The following pages contain flowcharts of the manufacturing process of Portland cement. Cement manufacturing process . Cement is mainly used to bind fine sand and coarse aggregates together in concrete. The aim is to keep transportation costs low. Basic constituents for cement (limestone and clay) are taken from quarries in these areas. A two- step process. Basically, cement is produced in two steps: first, clinker is produced from raw materials. In the second step cement is produced from cement clinker. The first step can be a dry, wet, semi- dry or semi- wet process according to the state of the raw material. Making clinker. The raw materials are delivered in bulk, crushed and homogenised into a mixture which is fed into a rotary kiln. This is an enormous rotating pipe of 6. This huge kiln is heated by a 2. The kiln is slightly inclined to allow for the materials to slowly reach the other end, where it is quickly cooled to 1. Four basic oxides in the correct proportions make cement clinker: calcium oxide (6. These elements mixed homogeneously (called “raw meal” or slurry) will combine when heated by the flame at a temperature of approximately 1. New compounds are formed: silicates, aluminates and ferrites of calcium. Hydraulic hardening of cement is due to the hydration of these compounds. The final product of this phase is called “clinker”. These solid grains are then stored in huge silos. End of phase one. From clinker to cement. The second phase is handled in a cement grinding mill, which may be located in a different place to the clinker plant. Gypsum (calcium sulphates) and possibly additional cementitious (such as blastfurnace slag, coal fly ash, natural pozzolanas, etc.) or inert materials (limestone) are added to the clinker. All constituents are ground leading to a fine and homogenous powder. The cement is then stored in silos before being dispatched either in bulk or bagged. What is concrete? Concrete is a solid material made of cement, water, aggregates and often with admixtures. When fresh, it has a certain workability and takes the form of the mould into which it is put. When set and hardened, it is as strong as natural stone and resists time, water, frost, mechanical constraints and fire. Typically, concrete is the essential material used in all types of construction. Lafarge is a leader in the use of alternative raw materials and fuels for fueling manufacturing operations. Cement Manufacturing Process. The kiln is at the heart of the manufacturing process.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
January 2017
Categories |