Grinding Circuit Control Strategy

Figure 4 is a schematic diagram of a ball mill/cyclone control system. This diagram shows the instrumentation and the calculated variables used in the control strategies. The prior detailed process analysis study produced two major conclusions: Reduce mill feed size Reduce ball charge size The reduction of the mill feed size could be reduced by … Read more

Lime Burning Operation Heat Energy Requirements

There are two types of lime, high calcium and dolomitic lime. Typical analyses of these materials are shown in Table 1. This discussion is concerned only with high calcium lime. Lime is produced from naturally occurring limestone by subjecting the limestone to a temperature in the range of 2200°F for sufficient time to drive off … Read more

Tailings Belt Filter Press

Crushed ore is reclaimed in a 3.7 m (12′) diameter tunnel with, two variable speed slot feeders. Mill feed is conveyed to a 3.7 m x 1.2 m (12′ x 4′) 250 hp semi-autogenous (SAG) mill. Lime is screw fed onto the conveyor inside the reclaim tunnel. The SAG mill discharge enters a common sump shared … Read more

Flotation Hydrodynamic

The Bureau of Mines conducted research on the flotation hydrodynamics of fine particle flotation to improve the flotation efficiency in our domestic minerals industry. The turbulent fluid velocity profile was measured in various flotation cells at different levels of dissipation energy. The importance of dissipation energy and bubble size within the flotation cells for the … Read more

Effect of Turbulence in Fine Bubbles Flotation

The U.S. Bureau of Mines examined the influence of turbulence on the fine bubble flotation of fine-sized (minus 10 micron) galena in order to improve flotation efficiency. Fine bubble flotation was carried out in a spinning-disk flotation cell and was compared to results obtained from flotation in a conventional cell at equivalent agitation levels. An … Read more

Redox Electrodes & Mineral Floatability

Gold spiral electrodes were fabricated as a 3-turn coil of 10 cm long wires of 0.5 mm diameter. Following the hypothesis that a black platinum electrode follows more closely the solution potential than the mineral potential due to its high porosity (area for contact with the solution being much larger than the projected area for … Read more

Slurry Volume Hold-Up of Overflow Ball Mills

Figure 1 shows the head-on view of a typical overflow discharge mill including the definition of symbols and specific mill volumes to be used. In this discussion it is assumed that the overflow discharge mill being operated at steady-state will demonstrate a reservoir effect, that is that the Volume 1 of Figure 1 will be … Read more

Carlin Trend Geology

Stratigraphy The stratigraphic sequence in the Carlin Trend Geological area is Lower Paleozoic marine sediments and Late Tertiary tuffaceous sediments. The Lower Paleozoic sediments consist of the Siluro-Devonian Roberts Mountains Formation, the Devonian Popovich Formation and the locally named Rodeo Creek Formation. The Rodeo Creek Formation had previously been described in the mine area as … Read more

Jarosite Production

Jarosite Production: The roast-leach-electrowin process for zinc production involves roasting zinc sulphide concentrate to produce calcine containing zinc oxide. Zinc concentrate roasted at Risdon typically contains about 11% iron, which is predominantly converted to zinc ferrite (ZnFe2O4) during the roasting operation. When the calcine is leached under weak acid conditions (pH ≤ 2) only the zinc oxide … Read more

No Conditioning Carbonate Flotation

Tests to study the effect of collectors and pH were randomly conducted on the phosphate matrix, using a 2k full factorial design for collector screening and process optimization. Star points needed to estimate non-linear factor responses were included in the optimization test series and in some reagent screening tests. For the fatty acids, the two … Read more