Liberation size

There is some beneficiation of talc by froth flotation (qv), practiced especially on ultramafic-type deposits. In this process (Fig. 2), talc is milled to its liberation size (—100 mesh (ca 0.15 mm)) using ball mills or ring-type roller mills and then slurried at 10—30% in water. Flotation is done in conventional multistage float cells using methyl amyl alcohol as a frother. Typically two to four stages are required to upgrade the ore from 50—70% talc to 90—98%. The product is filtered and then flash-dried and milled to a final product. 

With regard to specific types of equipment, the safety factor practices of some 250 engineers were ascertained by a questionnaire and summarized in Table 1.4 additional figures are given by Peters and Timmerhaus (References, Section 1.1, Part B, pp. 35-37). Relatively inexpensive equipment that can conceivably serve as a bottleneck, such as pumps, always is liberally sized perhaps as much as 50% extra for a reflux pump. In an expanding industry it is a matter of policy to deliberately oversize certain major equipment that cannot be supplemented readily or modified suitably for increased capacity these are safety factors to account for future trends. 

The particle size of the tungsten ore which determines the degree of disintegration necessary to liberate the tungsten mineral (liberation size). 

Beneficiation of tungsten ores by gravity was the classical method, followed by a cleaning step (Fig. 5.1). The recovery depends on the ore characteristics (mainly liberation size) and ranges typically between 60 and 85%. The main loss is in the slimes, because the tungsten minerals are the most fiiable ones present in ores. 

Consider using dense media separation to preconcentrate before grinding to final liberation size. 

Use feed assay and liberation size as criteria to guide selection of options. 

Consider wet processing for particle diameter <6 mm to minimize dusting and electrostatics. For particle diameter >150 pm, prefer wet belt <150 pm, prefer wet drum. Match magnetic gradient to the diameters of the particles. Match the machine to the liberation size (liberation size is 0.01 of the diameter of the mineral crystal). For wet machines, pump 4 Mg water/Mg sohds, although 90% of the water can be recirculated. 

For minerals, the liberation size is 0.01 of the diameter of the mineral crystal. 

Match magnetic gradient to the diameter of the particles. Match the machine to the liberation size (liberation size is 0.01 of the diameter of the mineral crystal, Section 5.18). 

Compared to the other flotation systems, the material is much coarser in potash flotation, due to a large liberalization size of the crystals. The rather small difference in density between the mineral salt and the brine makes it possible to float much larger particles in the brine system as compared to water systems. 

The minable zone of the Esterhazy Member is reasonably thick and high in grade, has a low insolubles content, and is overlain by a comparatively strong strata ( roof rock). An approximately 2.4-m-thick zone of the Esterhazy Member is mined at three locations GMC Kl, IMC K2, and PCS Rocanville). The ore from the Esterhazy Member averages 25% K2O and 1% insolubles. Some carnallite is present in the ore, varying from less than 1% (normal) to as much as 10%, The sylvite liberation size is unusually large (much of the ore is liberated at plus 3-mesh [Tyler] or plus 6.7 mm). 

The beneficiation of raw potash ore into marketable products, similar to potash mining operations, requires a somewhat efferent scheme and equipment for each processing plant. The ore composition (mineralogy), ore grade (K2O content), liberation size (amount of masd-mum particle size required to attow separation of the different minerals), and type and amount of slimes (insolubles such as clay, anhydrite, dolomite, silica, etc.) are different for every deposit, and perhaps may be h W variable writhin a single deposit. Accordingly, themodr, ern potash processir plant must have an ef ient, hic y versatile process to accommodate variations in the feed yet still maintain product quality at as low a production cost as possible. 

The second and third stages of grinding and classification involve even greater choices of equipment, but are relatively more expensive. For small liberation sizes (usually between 100- and 150-mesh, Tyler), wet ball or rod mills are required. For larger liberation sizes (plus 100-mesh, Tyler), wet or dry impactors or cagemills are... 

Peptide self-assembly High control over liber size, diameter, and spatial patterning bioactive degradation mimic biological extracellular matrix Expensive limited scaffold size limited mechanical properties 67,68,74,75... 

In 1960 the maximum haul for the ore to the plant was 800 m, and 670 m for the overburden to the tailings pile. Primary gyratory cmshers first reduced the ore to a —15 cm (—6 in.) size, and then it proceeded to a series of size reduction and screening steps until its liberation size had been reached for a flotation separation (in 1960 there was also heavy media separation). Prior to flotation the ore was acid washed and then given an abrasive scmbbing to remove stains on the crystal surfaces... 

A detailed laboratory study has been presented by Dresler et al. (1998) on the Roast, Acid-Leach Process that exactly follows the process previously used by the LCA (now EMC) at their North Carolina deposit. It is reviewed here because of the additional details that it supplies on this very effective spodumene process. Their ore was from Wekusko Lake, Manitoba, which as at LCA s deposit was an unzoned and low-grade (0.79% Li) spodumene ore, but with a very small crystal size. Electron micrographs showed that each of the minerals in the ore (Table 1.18) was present as discrete crystals, but the liberation size was quite small. Consequently, they ground the ore to a —212 p,m (—65 mesh) size, and made into a 23% slurry to be agitated and conditioned with 2 kg of sodium hydroxide/mt of ore for 20 min. 

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