Single stage crush/single stage SAG mills and two stage crush/ball mill circuits are typically selected for low throughput plants (<50 t/h) where personnel costs are a large component of costs. SAB circuits are typically selected for plants of 0.5 to 2 Mt/a.
2020518&ensp·&enspA ball mill efficiently operated performs a wide variety of services. In small milling plants, where simplicity is most essential, it is not economical to use more than single stage crushing, because the SteelHead Ball or Rod Mill will take up to 2 feed and grind it to the desired fineness. In larger plants where several stages of coarse
closed circuit ball mill. The Australian experience of milling lateritic ore is to use a highaspect ratio mill at the initial stages of operation using a singlestage circuit. With time, as the hardness of the ore increases with depth in the mine, a secondstage ball mill is added.
The first two types may be called singlestage operation, while the last two are twostage operations. Most AG/SAG mills operate in open circuit (Figure 9.3) when the product size is usually coarse.Usually, provision exists for installing a classifier such as a straight screen, a trommel or a curved DSM screen to remove critical sized pebbles (scats).
2014101&ensp·&enspSINGLE STAGE SELECTION CRITERIA The decision to go single stage or two stage grinding is generally dictated by the product required. A guide based on grind size follows: 1. Coarse Grind Coarser than 80% passing 106 µm. If determined to be reasonably powerefficient, single stage SAG milling is likely to be the most profitable grinding circuit
2020516&ensp·&enspThe comparison between single stage and double stage grinding has received much attention in the past few years. In order to submit information for use of mill operators, we have prepared comparative flowsheets for 50 Ton, 100 Ton, 200 Ton, 350 Ton and 550 Ton/24 hour plants, showing both single and twostage grinding in typical mill flowsheets. These flowsheet comparisons show the
2018220&ensp·&enspSINGLE STAGE BALL MILLS Single stage balls add to the argument that rotary mills are not efﬁ cient when processing large hard material. If a single stage ball receives material of 80 per cent passing 6 mm and larger, then the Bond oversize inefﬁ ciency factor EF4, will apply even if the material has rod and ball mill laboratory work indices as