Mineral Processing Engineering

The grade of the feed to the concentrator averages 0.9 g/t Au, 110 g/t Ag, 1.1% Cu, 2.8% Pb, 9.2% Zn, 5.0% Pyrite-S and 13% BaSO4.

Recently, a new automatic reagent control system was developed by Dowa Mining Co., Ltd. This system consists of On-Stream X-ray Fluorescence Analyser (OSA), Central Processing Unit (CPU), Cathod Ray Tube (CRT) and Control Units. This system calculates the material balance and flotation rate constants in the circuit based on the OSA assay data, and then predicts the assay of flotation products. According to the prediction, reagent additions at five points are automatically controlled.

The flotation is characterized by the adoption of SO2-lime method and hot pulp flotation, both of which are developed in Kosaka concentrator of Dowa mining Co., Ltd. After the conditioning with H2SO3 solution and lime, Cu.Pb bulk flotation is carried out according to the flowsheet. Cu.Pb bulk concentrate is then treated by means of hot pulp method to separate it into copper and lead concentrates. The tailing from the Cu.Pb bulk flotation goes to the zinc flotation, where zinc concentrate is recovered by conventional method. This new system has the following features.

1. With this system, nine different sample flows can be treated at
   

Several reasons contribute to the wide gap in the industrial application of the academic models. These include: 1) the lack of generality in the model, e.g., the model is limited to certain size ranges; 2) the academic models involve complicated mathematics 3) confusion about the order of the flotation rate, e.g., several authors proposed a first order rate model, whereas the others propagated a second order rate model 4) the use of an unrealistic rigid value, such as the use of a maximum recovery of 100%, which is unrealistic in industrial operations; and 5) the use of graphs that confuse the reader rather than interpret information.

The standard procedure in the laboratory rougher flotation testing was as follows: 1500 g of sample was ground in the presence of lime at 60% solids to a specific grinding requirement. The pulp was then transferred to a 5.8-liter Denver cell. Flotation chemicals were added and the pulp level adjusted to the 4.4-liter level. After conditioning for 30 sec, flotation was started. The froth was collected at intervals which were more frequent in the beginning and less frequent to the end.

The flotation rate of copper is proportional to the residual recoverable fraction of copper and

The depressing effects of different inorganic chemicals on the flotation of pyrite have been investigated in this study. The results of the flotation tests indicate that pyrite can be depressed by oxidizing as well as reducing agents under controlled conditions of pH and reagent dosage. Oxidizing reagents such as potassium chromate and potassium dichromate were found to cause complete depression of pyrite in the acidic pH range. These effects are similar to those obtained in the pyrite-cyanide system. A less stable oxidant, potassium permanganate, inhibited the flotation of pyrite at a concentration as low as 0.1 mol/L at all pH values. Addition of reducing chemicals such as ferrous chloride or manganous sulphate to the flotation of pyrite were found to produce depressing effects depending on the additive concentration and pH of the solution.

Experimental

Massive pyrite was crushed and dry ground in a porcelain ball mill. The 100/400 mesh fraction was separated by wet screening with tap water, and panned to remove the small amount of silicates present as inclusions, and deslimed. The cleaned sample was given a final wash with 0.1 M HCl solution to remove the adsorbed impurities, and thoroughly rinsed with distilled deionized water.

Collector (KEX): Commercial Potassium

The development of larger size flotation machines, which started in the 1950’s and 1960’s, is still proceeding. The largest mechanical flotation machines available today have unit volumes in the range of 38 to 42 m³ (1,350 to 1,500 cft). In fact, the motivating forces of increasing capital and energy costs and decreasing ore grades, which created the need for large flotation cells, not only still exist, but are becoming more critical.

The development of the Dorr-Oliver Flotation machine was initiated as a result of an industry need for more efficient mechanical flotation performance. The cost pressures facing the minerals industry today are severe and result from a variety of factors including:

a) Low product demand and depressed prices
b) Older process equipment with low energy efficiency
c) Poor productivity
d) High labor costs
e) Falling ore grades

Design Considerations

The purpose of the rotor in a mechanical flotation cell is two-fold. First, it must perform the task of a pump in maintaining the suspension of solids throughout the lower portions of the tank. Second, it must produce the required quantity of fine air bubbles and effectively disperse them into the slurry.

The guidelines called for a small diameter energy efficient rotor that would operate as an efficient