Largest limestone calcining plant in China triples output with use of Metso equipment

Metso has installed three 1,100 t/d lime calcining rotary kilns at the Dongshan mine in Shangxi Province, China. This is the largest capacity limestone calcining plant in China. The customer is Taiyuan Iron and Steel (Group) Company (TISCO) and this installation marks the first time that TISCO has used rotary kilns for lime production. The three lines of calciners produce a total of 3,300 t/d of high reactivity lime for use by TISCO in the production of 3 Mt/y of stainless steel. Each line is fired by a combination of coal and natural gas, and operates with an 18-module polygonal pre-heater that uses KVS/Niems coolers. The improvements on the original cooler design provided by Metso are granted US patents.

Metso was selected from international competition to complete the contract, and according to Qi Song (Vice President, Projects and Systems Sales, Metso Minerals China) it was a combination of factors that led to TISCO’s decision to use Metso kilns. “Our expertise in Metso Pyro was well known,” he says, “and we have proven product and design experience.” Additionally, says Song, “Our understanding of minerals processing in general and the needs of the TISCO project in particular helped us develop the right sales strategy.”

A significant issue to resolve for TISCO’s stainless steel production was a bottleneck in lime production caused by three shaft kilns of limited capacity, processing a combined total of only 1,100 t/d. Metso’s more efficient kilns not only triple this output but operate with fewer maintenance problems than the kilns they replaced. There is also a beneficial impact on the environment. “Because of the flexibility of operation control in the kiln systems,” says Song, “there is less fuel and power consumption, and fewer emissions into the atmosphere.”

Metso was responsible for process design, detail engineering, key equipment supply, control system, supervision service, commissioning and start-up, the plant included significant Chinese-manufactured equipment, built to Metso’s designs and specifications. Spare parts and support for continuing site operations from service engineers comes from the Metso Minerals China office.