General overview of the copper, lead and zinc smelting plant in India

Zinc, copper and lead are indeed counted among the essential metals used worldwide. No really good alternatives are available for these metals, considering their specific chemical and technical properties. Thus, establishing a copper, lead and zinc smelting plant becomes the need of the hour to meet the increasing demand.

Smelting is a process by which a metal is obtained, either as a simple compound or as an element from its ore. This is done by heating the metal beyond its melting point in the presence of oxidising or reducing agents like air or coke. Thus, smelting is a pyrometallurgical process. Surprisingly, the first metal to be smelted in the ancient Middle East was perhaps copper. This was followed by tin, lead, and silver. So, continuing this age-old practice by establishing a copper, lead and zinc smelting plant can reap various benefits.

There are three types of smelting, namely –

Matte smelting is carried out in a flash smelter or reverberatory furnace. No reducing agent is used in matte smelting. Slag and matte are obtained as end products.

Reduction smelting: This process occurs in an electric or blast furnace. In reduction smelting, the ore is reduced by carbon in the presence of flux to generate slag and molten metal.

Flash smelting: This smelting process is mainly used for sulphur-containing ores.

Importance of copper, lead and zinc smelting

Before setting up the copper, lead and zinc smelting plant, it is vital to understand its importance. Notably, these three metals are crucial in changing society towards a circular economy. They are the primary source of the metals needed for all new technologies. Also, the supply of these metals depends on the hydrometallurgical extraction from ore concentrates. Copper is used in vast amounts for new energy generation technologies. Thus, the demand may grow more than predicted and more than the industry can offer. Thus, smelting becomes reasonably necessary.

Benefits of establishing the copper, lead and zinc smelting plant

• Low investment and operating costs
• Proven and reliable process and equipment
• Potential to treat various qualities of raw materials with variable feed rates
• Meets the strictest environmental requirements
• High recovery of valuable metals like copper, lead and zinc
• One can easily employ the cleanest smelting process

Essential documents and certificates

The following documents are mandated to set up copper, lead and zinc smelting plant in India -

• Environmental impact assessment (EIA) certificate
• Process plant layout
• Identification documents concerning the land where the processing plant will be set up
• Identification documents of the applicant, if a corporate body, the memorandum and articles of association, certificate of incorporation and registered address must be provided
• Pollution License

Mandatory documents for Pollution License

• Process flow diagram (production details)-manufacturing process
• Capital investment on plant, land and machinery (balance sheet/CA certificate/capital investments)
• Land ownership documents (rent agreement/sale deed)
• Detailed layout of the factory premise showing water supply line, structures, sewers for domestic and trade effluents, storm drain, location of effluent treatment and its disposal and any other helpful detail, tables, drawing, etc.
• The complete proposal of the pollution control system
• NOC by the local body for the proposed industry
• PAN and Aadhaar cards of partners/proprietors/directors
• A copy of the PAN card industry
• Previous consent copy (For renewal only)
• Index/site plan indicating the nearby area like town, village, river, transport routes, sea shore, etc.
• Additional documents, if asked by the authority.
• Latest Joint Vigilance Sample analysis report (JVS report)
• Aadhaar and PAN card of the authorised person
• Company authorisation letter
• Industry Board resolution/list of partners of the company/list of directors
• Information of chemical reactions with mass balance
• Product mix format
• Environmental Clearance of Government of India (if applying for consent to operate(CTO))
• Latest analysis report of fuel gases, effluent, solid waste and hazardous wastes
• Ambient Air Quality report
• TLV (Threshold Limit Value) of raw material
• Ambient air quality report
• Water budget calculation

Detailed process to obtain Pollution Licence

The concerned PCB issues pollution NOC in two stages – CTE (Consent to Establish) and CTO(Consent to Operate). The following table states the complete process to obtain the NOC.

Complete information elaborating on the smelting process

Three processes occur at the copper, lead and zinc smelting plant. These are as follows -

Copper Smelting

Conversion of copper from ore to metal is done by smelting.

1. During the process, the concentrates are dried and fed into one of many different types of furnaces.
2. Subsequently, the sulphide minerals are partially melted and oxidised. This is done to produce a mixed copper-iron sulphide, a layer of matte and slag, and an upper layer of waste. The matter is further converted.
3. The slag is tapped from the furnace and discarded or stored in slag piles onsite. A small amount of slag is sold for sand-blasting grit and railroad ballast.
4. A third product of the copper smelting process is sulphur dioxide. It is a gas purified, collected and converted to sulphuric acid for sale or use in hydrometallurgical leaching operations.

Besides copper smelting, two other processes are carried out in India's copper, lead and zinc smelting plants.

Lead Smelting

1. During the lead smelting, a sinter obtained from pre-processing is fed into a blast furnace and various recycled and clean-up materials, coke, limestone and other fluxing agents. This process is carried out for reduction, where the carbon acts as a fuel and smelts or melts the lead material.
2. The molten lead then flows to the bottom of the furnace where four layers are formed: “matte” (other metal sulphides and copper sulphide); “speiss” (the lightest material, basically antimony and arsenic); lead bullion (98% lead, by weight) and blast furnace slag (mainly silicates).
3. All layers are then drained off. The matte and speiss are sold to copper smelters for recovering precious metals, including copper.
4. The blast furnace slag, which comprises iron, zinc, silica and lime, is stored in piles and partially recycled.
5. Sulphur oxide emissions are produced in the blast furnaces from small quantities of lead sulphates and residual lead sulphide in the sinter feed.

Another vital process at the copper, lead and zinc smelting plant is explained below.

Zinc Smelting

1. Electrolytic zinc smelting plant comprises as many as various hundred cells.
2. A fraction of the electrical energy is transformed into heat, raising the electrolyte's temperature.
3. Electrolytic cells operate at temperature ranges between 30 and 35°C at atmospheric pressure.
4. During electrowinning, a part of the electrolyte passes through cooling towers to evaporate the water it collects and reduce its temperature.

Standards for emissions or discharge of environmental pollutants

Establishing a copper, lead and zinc smelting plant may seem lucrative. But it must also be taken care of that the unit abides by the norms of various environmental laws and compliances. One of them is the Environment (Protection) Act.

So, to protect and improve the quality of the environment along with abating and to prevent environmental pollution, the norms for discharge or emission of environmental pollutants from the operations, industries or processes must be as mentioned in 2[Schedule I to IV] of the E(P) Act.

The standards for the discharge or emission of environmental pollutants mentioned under sub-rule (1) or (2) must be adhered to by an operation, industry or process within one year.

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