The flotation method is a widely used technique for the recovery of gold from gold-containing copper ores, base metal ores, copper-nickel ores, platinum group ores and many other ores where other processes are not applicable. Flotation is also used for the removal of interfering impurities before hydrometallurgical treatment, for upgrading of low sulfide and refractory ores for further treatment. Flotation is considered to be the most cost-effective method for concentrating gold.
Flotation process maximizes the enrichment of gold into sulfide minerals. The tailings can be directly discharged. In China, 80% rock gold is processed by flotation for its low cost.
Gold Flotation Process
is use to process fine gold, high floatability of sulfide gold-bearing quartz veins ore , multi metal gold-containing sulfide ore and carbon-containing ore.
In the flotation process of the major steps that must be done include:the process destruction of rock minerals, milling, flotation, drying and smelting.
The process of destruction of rocks minerals and grinding
In this process of rock minerals that have been taken from the mine site and then destroyed by the machine to obtain a fine grain of sand to free metal-containing granules for further processing. In the destruction of mineral rocks of machine tools can use a stone crusher machine, so the minimum size of rock minerals can reach between 28 mesh.
The Process Of Flotation
At this stage after a mineral ore that is refined inserted into the machine agitator tank which is usually also called a flotation cell to produce a pulp slurry concentrate.Distilled water provision inserted into the flotation cell flotation machine is then run, examined the amount of initial pH and initial temperature. In the flotation tank, stirring with impellers, which are intended to produce turbulent motion of fluids (pulp), so that when inserted air flow will form air bubbles.In the pulp is then coupled collector-1,-2 collector and frother; flotation machine run back to the time varying adjustment, and examined the amount of the final pH and final temperature.
In the process flotation reagent which in use is a form of lime, bubble and collectors. Froth forming a bubble that is stable and that float to the surface as a froth flotation cell. Collector reagents react with the surface of the precious metal sulfide mineral particles making the surface is water repellent. surface of the mineral-bound water molecule is released and will be changed to hydrophobic.
Thus the collector end of the hydrophobic molecules will be bound hydrophobic molecules from the bubble, so the mineral ore can be adrift. Collector has a molecular structure similar to the detergent hydrophobic sulfide mineral grains are attached to the air bubbles that rise from the slurry zone into the froth that floats on the surface of cells.
In the flotation process of air bubbles formed initially has small size and some are attached to the surface of mineral particles. Furthermore, another air bubble formed next to join the existing air bubbles and form air bubbles with a larger size, so as to have sufficient lift to lift mineral particles to the surface. The mechanism of attachment of mineral particles in the air bubbles inside the tank during the flotation process flotation occurs when the hydrodynamic forces and the forces of interaction between mineral particles with air bubbles, resulting in collisions with air bubbles and mineral particles occurs attachment of mineral particles with air bubbles.
From the results of bubble froth flotation process that resembles acolored foam detergent concentrate metallic ores carrying gold-copper mineral-laden is then up to the tub shelter, and foam concentrate that has been lifted from the drain into the upper lip and into the trough flotation machine is in use as a valuable mineral collection.
The Process Of Drying And Smelting:
Valuable minerals that have been collected in the form of concentrates and mineral ore slurry 65% solids by weight in dry with the dryer until the water content there is only 9%.
After all is finished and dry the gold and copper ore concentrate is ready for processing into thesmelting.
In order for the flotation process can take place by either means of attachment of particles to air bubbles lasted until the top edge of theflotation cell, it is necessary to consider the following matters :
- Particle size on flotation process should be quite small, usually smaller than 65 # (205 μm).
- Viscosity mud (pulp) while the flotation process takes place in theflotation cell typically ranges from 25% to 45% solids. Viscosity is toohigh can lead to bubbles is difficult to lift up, but the viscosity is toolow will reduce the capacity.
- In the process of flotation of air bubbles must be sufficiently largeand stable so as to lift solid particles up to the lip of the cell. Airbubble is stable, meaning not easily broken and very dependent on the type and amount of frother used.
- Surface of solid particles that will float must be hidrofobi, while that will not float must be hydrophilic. These properties can be achievedby adding an appropriate flotation reagents.
- Use of reagent should be appropriate quantity and needs, and addedat the right time.
- When used in flotation cells equipped with impller, then spin the impeller at the time of flotation process should be made in such amanner as not to break up air bubbles that have been plastered byhidrofobi particles.