Calcium Carbide (CaC2) is outcome of chemical reaction of quick lime (CaO) with carbon (C). Both these raw materials react at very high temperature of about 1800 °C -2100 °C to produce Calcium Carbide. Chemical reaction involved is as under
CaO + 3C -> CaC2 + CO (Stage 1)
CO + O2 -> CO2 (Stage 2)
Quick lime and Carbon materials, in predetermined proportion, are fed to the furnace where electro-thermal reduction reactions take place to produce Calcium Carbide in molten state.
Electrical energy is supplied in the submerged arc furnace for the Calcium Carbide production. Calcium Carbide in the molten state is tapped out of the furnace which is mostly used for production of Acetylene gas for in-house manufacturing of PVC resin and/or partially sale in market as Raw Carbide.
Acetylene gas production is forward integration of Calcium Carbide manufacturing process. Acetylene is an outcome of chemical reaction of Calcium Carbide with water. Chemical reaction involved is as under
CaC2 + 2H2O > C2H2 + Ca(OH)2
Acetylene gas, as obtained during the chemical reaction mentioned above is onward utilized for PVC resin manufacturing.
PVC resin is manufactured by polymerization of Vinyl Chloride Monomer (VCM). VCM is manufactured from reaction of Acetylene gas (C2H2) & Hydrochloric Acid (HCl). The C2H2 & HCl are produced in the Calcium Carbide Plant & Caustic Soda Plant within the integrated complex of DCM Shriram, Kota.
DCM Shriram has undertaken various initiatives related to water conservation and harvesting. The management commitments and support from employees and other stakeholders have helped Kota complex to reduce its fresh water consumption by 67% and reduced effluent generation quantity by 93% in the last three decades.
The above milestone was achieved in-spite of production capacities increasing manifold. PVC Resin plant has increased production capacity while the specific water consumption has reduced by 9% through implementing various water saving initiatives including recycling/reuse of treated effluents, operation of existing cooling towers on higher COC and creating awareness among all the employees by conducting various programs, seminars & sessions and continual pursuance to Reduce, Reuse and Recycle (3R) the water wherever possible.
Some of the Reduce, Recycle & Reuse (3R) initiatives includes replacing old polymer with new efficient polymer of higher capacity, aeration system for raw water prior to pre-treatment to increase the O2 level in water thereby reducing organic load in water resulting in less effluent generation, optimizing VC scrubbing water in PVC production process for reducing fresh water consumption etc.
The above efforts have been recognized by CII in 8th Water Innovation Summit as “Noteworthy Water Efficient Unit” at the National Competition for Excellence in Water Management 2022.
Calcium hydroxide sludge is generated in the process of manufacturing PVC resins through calcium carbide route, which is then converted to cement in an environmentally friendly manner using 'wet' process. The Company produces high quality, premium grade Pozzolana Portland Cement and Ordinary Portland Cement. The Cement is characterized by light colour, superior strength and early setting properties. This case of circular economy has helped the company utilize the by-product generated from one plant into another value product.
The Company has taken several initiatives for energy conservation and greenhouse gas (GHG) reduction under six sigma projects. One of the most impactful initiatives undertaken is bulk transportation of PVC to PVC Compounding plant that has resulted in elimination of HDPE bags usage, which subsequently reduces GHG emission. Heat generated from one of the furnaces is gainfully utilised in the Waste Heat Recovery Boiler for the generation of steam which eliminates additional utilization of fuel.