Question

Define Gravity Concentration and list five separators that may be used for either roughing or cleaning operations.

b. Explain the role of the following as used as flotation reagents i. Collectors

ii. Frothers iii. Regulators

detailed answer so i will understand please

Answer 1

ANSWER- Gravity concentration- It can be defined as a process of separating minerals based on the differences of their specific gravity. This process is specially used for recovering very high grades of valuable ore material into very small masses. It is a significant process of obtaining minerals due to its simplicity and less harmful impact on environment.

The five separators that may be used for either roughing or cleaning are as follows:-

1. Electric Separator- It separates the minerals constituting the feed material based on the differences in their electrical conductivity.
2. Magnetic Separator- These low intensity separators are used to treat highly paramagnetic materials and some ferromagnetic materials.

In the following class of drum separators, the minerals and dense medium are fed into a large quiescent pool or tank or trough of the medium. Particles denser than the medium will sink and the low specific gravity particles float. The floating material overflows or is removed from the bath by scrapers while the sink material falls to the bottom of the tank and is removed by some means. The many types of static bath separators include those used for coal separation and mineral separation.

1. Drum Separator- It consists of a cylindrical rotating drum, used for mineral and coal separation. The floating product overflows from a weir at the opposite end to the drum feed.
2. Drewboy Bath Separator- It is used widely in the cleaning of coal. The coal is fed into the bath at one end and the floats scraped from the opposite end while the sinks are lifted out from the bottom of the bath by the vanes of a slowly revolving inclined wheel.
3. Cone Separator- It is used for ore treatment since it has a relatively high sinks capacity. The feed is dropped into a gently agitated media bath. The floats overflow a weir while the sinks product is removed directly from the bottom of the cone shaped vessel by pump or by an air lift.

The role of flotation reagents:-

1. Collectors- Collectors are reagents that are used to selectively adsorb onto the surfaces of particles. A monolayer is formed by the collectors on the particle surface that essentially makes a thin film of non-polar hydrophobic hydrocarbons. The collectors greatly increase the contact angle so that bubbles will adhere to the surface.
2. Frothers- The principle of froth floatation is that sulphide ores are preferentially wetted by pine oil, whereas the gangue particles are wetted by water.Collectors are added to enhance the non-wettability of the mineral particles. Examples of collectors are pine oil, fatty acids and xanthates. Froth stabilisers are added to stabilise the froth. Examples of froth stabilisers are cresols, aniline. If two sulphide ores are present, then it is possible to separate the two sulphide ores by adjusting the proportion of oil to water or by adding depressants.
3. Regulators- The function of regulator is to modify the alkalinity or acidity in flotation circuits, which is commonly measured in terms of hydrogen ion concentration, or pH. Modifying the pH of a pulp has pronounced effects on the action of flotation reagents and is one of the important means of making otheriwse difficult separations possible.