Tuesday, April 4, 2017

Manufacturing processes & Wastewater characteristics for Cement industry

Manufacturing processes & Wastewater characteristics for Cement industry
The major contaminant from cement industry is SPM and RSPM in the form of dust due to mining and grinding operations involved in the process. Hence, cement industries contribute to air pollution and virtually zero water pollution.
Cement is a compound madeup of
  • calcium oxide and 
  • silicon dioxide along with 
  • aluminium oxide, 
  • ferric oxide and 
  • magnesium oxide. 
 Raw materials required for the manufacture of cement are
  • lime
  • sand
  • clay
  • shale
  • iron ore and
  • blast furnace slag
In order to manufacture cement, the raw materials are passed through the following six phases:
  • Raw material extraction / Quarrying
  • Grinding, Proportioning and blending
  • Pre-heater phase
  • Kiln phase
  • Cooling and final grinding
  • Packing and shipping
Several cement plants have made a sustained effort in controlling and regulating emissions by using air pollution control devices like electrostatic precipitators and bag filters. Fugitive emissions in cement plants is still a problem

  • In cement industries, water is used only for cooling operation of manufacturing operation. Process wastewater with high pH and suspended solids may be generated in some operations. Water used for cooling is recycled and reused. Screening along with settling basin and clarifier is used for reduction of suspended solids. Treated water from wastewater treatment plant is used for development of green belt which helps in reducing noise pollution. Storm water flowing through pet-coke, coal and waste material stock piles exposed to the open air may become contaminated with high amount of sulphates, toxic metals like zinc, lead and chromium present in dust. Contaminated water from cement manufacturing industry may leach into the ground and contaminate groundwater with excessive TDS.
  • The major sources of contaminants in water due to cement industry are:
  1. Cooling water and
  2. Wet scrubbing of kiln dust that yields an effluent with a high 
    1. pH value
    2. Alkalinity
    3. Suspended and dissolved solids like sulphates and potassium
The flowchart for manufacturing process in the cement industry is shown below:

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