Position: Weighing and process control specialist Procon Engineering has recently installed and commissioned phase one of a major belt scales turnkey project used in metal mining in Kazakhstan.
This prestigious project has involved the installation of 14 Inflo MS9600 Resometric belt weighing systems, three flow and density measuring systems and a rail weighbridge.
The weighing equipment is now providing essential management data on productivity at three sites centred around the city of Ust-Kamenogorsk in the east of the country.
Kazakhstan has long been a important source of lead, zinc, silver and other metals including gold and copper.
In order to effect rapid modernisation, programmes of investment are under way and the joint-stock company, Kazzinc JSC was created in January of 1997 resulting from the amalgamation of companies producing complex ore, zinc, lead and metal mining byproducts.
It represents a production entity with combined properties of joint-stock companies Lead and Zinc Combine (UKLZC), Leninogorsk Polymetallic Metal Combine (LPMC) and Lead Combine (ZLC).
The company, which is vital to the local economy, employs around 21,000 people and includes five mines, three mills, two zinc plants and one lead plant with a combined total annual capacity of about 420,000 tons of metal.
Ten of the belt scales have been installed at the Zyryanovsky and Maleevsky plants and mines, with a further two at the main processing plant in Ust-Kamenogorsk for weighing lead and zinc concentrates.
The rail weighbridge has also been installed here where it is used to weigh outgoing processed minerals.
The remaining belt weighers are working at the renamed Ridder Mine (formerly Leninogorsk).
The contract with Kazzinc was won against strong international competition and saw Procon's international sales manager, Des Redmond, spend extended periods in Kazakhstan.
Redmond is philosophical about his experiences and as he points out: "Enduring sub-zero temperatures and limited facilities proves that international selling is not always as glamorous as it is made out.
However, the satisfaction of winning this substantial order has made everything worthwhile.
We have extensive experience in applications involving the processing and refining of minerals, including lead, zinc and copper and I am convinced that the contract was awarded on the basis of technical excellence".
The belt scales have throughput capacities ranging from 10 to 700t/h and are used to weigh the raw material as it comes from the mine, again after it has been crushed, screened and subdivided and then finally after the mineral has gone through the flotation process.
The flow density meters are used to measure both the product and discard slurry densities.
The monitoring of the flow rate and density of discard slurry being pumped off to the lagoons provides important information on the concentration of minerals still present as "tailings".
By combining the extensive weight and density data from start to finish, managers can calculate what is known as the "plant balance" which is directly proportional to the overall process efficiency.
In the case of Maleevsky, a PC is used to interface with the belt scales, providing throughput tonnage data.
The material source indication is collected by the PC from a small PLC via a special serial link.
The PC then, using a shift management system, apportions the tonnage between each material type and logs the data on a per-shift basis.
Reports are automatically generated for shift, week and month with a summary of tonnage totals for each material type.
The client uses their LAN network to interface with the PC and collect the reports for further processing.
The Inflo Resometric belt scales are ideal for such arduous applications and provide a unique combination of features that ensure the key factors influencing belt scale performance are maintained in service over long periods of time.
At the heart of the scale is the Digital Resometric force transducer or resonator which provides unequalled levels of measurement performance that are repeatable for extended periods.
The resonator has no moving parts and is preloaded to a standard level by the applied force from the weigh carriage.
As the force varies with the load passing over the carriage rollers, the resonant frequency changes in proportion to applied load.
This change in frequency is processed by the electronics and combined with the belt travel to provide an accurate weight reading per unit time.
Periodic calibration checks can be carried out simply and expediently by utilising the built in calibration weights.
Lateral chains are fitted between the weigh carriage and the rigid conveyor to prevent any unwanted side forces being introduced by factors such as poor belt tracking or material asymmetry.
As a result, once the weigh carriage is installed and aligned, it only sees the vertical forces produced by the material being weighed by belt scale.
Phase one of the belt scales project is now well advanced and Kazzinc has issued Procon with instructions for a similar Phase two contract.