The Caijiaying lead zinc mine is located in China, north-west of Beijing, in Hebei Province. The region experiences severe winters, below -35°C, and warm summers, up to 30°C.
The mine and concentrator commenced operations in the second half of 2005 with a conventional tailings disposal system consisting of a tailings dam with peripheral ring main discharge and central water recovery. A second similar dam sharing one common wall was added later. In view of the extreme winter conditions tailings lines and ring mains plus spigots, together with return water lines, require insulation and electrical trace heating. The volume of process water trapped as ice in the tailings dam ponds each winter is significant. This seasonal variation presents a major difficulty in the management of process water availability.
Although Caijiaying is an underground mine there was no backfill plant at the start of operations. As plant throughput increased more quickly than originally anticipated, tailings storage capacity became a prime concern. The construction of a backfill plant in 2007 reduced the pressure on surface tailings storage area requirements, but as suitable land on which to construct further tailings storage was both expensive and difficult to acquire, a more efficient use of the available area was required.
Dry tailings storage, where flotation tailings are filtered to provide an immediate return of process water plus ‘dry’ tailings filter cake for stacking, provided an answer to both the land area required, and the water management difficulties.
The paper details the reasoning behind the change and the benefits obtained at Caijiaying by moving from ‘wet’ tailings storage to ‘dry’ tailings storage.
Waldram, J T and Jia, R, 2016. Caijiaying Dry Tailings Storage, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 379–382 (The Australasian Institute of Mining and Metallurgy: Melbourne).