Mining processes pose problems for concrete structures
Reinforced concrete is used widely in support structures (columns, beams and retaining walls), floors, channels and ore shoots, pipes, drains and tanks. In the mining of non-ferrous metals- the list includes copper, zinc, nickel, cobalt and manganese-reinforced concrete also has been used to fabricate the acid tanks, called containment cells. Although concrete provides an affordable tank solution in terms of upfront construction costs, the tanks’ high maintenance costs and short life cycles in these highly corrosive environments have prompted mining companies to seek more durable alternatives.
Composites in the form of polymers are providing the answer both in the design of newer cell structures and retrofitting of older cells, resulting in increased profitability and less downtime.
Extraction of nonferrous metals from crushed ore is accomplished by two processes: electrowining and electrorefining. In both processes, large quantities of heated acidic solution are pumped through multiple rows of electrodes contained in large vessels called cells. When electrical current is passed through the electrodes into the solution, purified metal is deposited onto the cathodes. These concrete electrolytic cells must support the weight of both the acidic solution and the electrodes. The cells also must stand up to the temperatures of the reaction as well as the extremely corrosive electrolyte solution.
The reinforced concrete containment cells are protected from the acid by a chemical-resistant but unbounded inner liner of either lead, polyethylene or polypropylene. However, the liners are prone to damage from falling electrodes and impacts from misaligned cranes (used to install and remove the electrodes). In addition, the liners become brittle with age and begin to crack. Damaged liners permit corrosive electrolytes to directly contact the cell’s concrete walls and floors, resulting in the erosion of rebars, causing catastrophic cell deterioration that eventually requires widespread repair. Cell maintenance costs, therefore, have been very high, especially when they calculated in terms of not only material and labor but cell downtime as well.
Today electrolytic cells are made from polymer concrete with bonded surface linings. In polymer concrete, a thermosetting polymer resin- epoxy, vinyl ester, polyester, furan or methyl methacrylate- replaces cement as the binder, with compositions typically ranging from 8 to 12 percent polymer by weight.
POLYMER CONCRETE INDUSTRIES (PCI)
POLYMER CONCRETE INDUSTRIES (PCI) is a South African registered company which manufactures polymer concrete electrolytic cells (POLYCELLS) in Africa for the base metal refineries. PCI and its associated companies have all been actively involved in the manufacture of equipment for the Chemical and Metallurgical Industries since 1981. PCI is owned by David Lawrence.
Polymer Concrete Industries (Zambia) Ltd (PCIZ) was registered in Zambia in 1999 and is wholly owned by PCI of South Africa. PCIZ was established in the Copperbelt region of Zambia to take advantage of providing quality Electrolytic polymer cells; cell-top fittings, lead anodes, sheet lead and ancillaries to rehabilitate the copper mines in both the Zambian and Congo markets.
PCIZ has been involved in both green and brown field projects in Zambia. Existing refineries in the Copperbelt region of Zambia as well as the new copper mines established in the Northwest Province are intent on using polymer concrete cells.
PCI manufactures POLYCELLS using expertise, technology and experience which are covered by registered Patents, SA Patent No. 98/10256 and ARIPO Patent No. 98/01411. PCI is Africa’s leading manufacturer of Polymer Concrete POLYCELLS, Spacer Blocks, Capping Boards, flooring protection; cell-top fittings Lead Anodes and Sheet Lead.
Its founder David Lawrence has been involved in the metals industry for over forty three years and was for many years the Managing Director of the largest lead foundry in Africa. PCI’s investment consists of the upgrading and modernizing of the existing lead rolling mill, foundry and lead extrusion press at Chambishi.
A new factory building has been built in which the manufacturing of cells and the new fully automated Anode rolling mill is installed.
The anode rolling mill is designed to produce hot rolled lead anode blades for the use in electrolytic recovery of zinc, copper, nickel and cobalt refineries. Lead sheeting in various thicknesses is also produced.
Leading manufacturers of:
- Polymer Concrete POLYCELLS
- Cell Capping Boards
- Polymer Concrete Spacer Blocks
- Lead Anodes
- Lead Sheets