Exploring Froth Flotation & Negative Energy of Activation

In summary, froth flotation is a technique used for ore concentration where mineral particles are separated from waste material through the use of frothing and collecting reagents. Negative energy of activation, on the other hand, is an apparent effect in some reactions, where the product of the rate constant and equilibrium constant may decrease with increasing temperature, despite the rate constant increasing. This phenomenon is seen in the oxidation of NO to NO2.
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Evil
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does anyone here has any idea what is froth flotation(in extraction pf metals) and negative energy of activation( as in chemical energetics)?
thanks for any input.
 
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  • #2
Froth flotation is an ore concentration technique commonly used with (hydrophobic)sulfide ores (such as iron or copper pyrites). Crude ore is ground to a fine powder and mixed with water, frothing reagents, and collecting reagents. When air is blown through the mixture, mineral particles cling to the bubbles, which rise to form a froth on the surface. The waste material (gangue) settles to the bottom. The froth is skimmed off, and the water and chemicals are distilled or otherwise removed, leaving a clean concentrate.

For more discussion, see http://www.engr.pitt.edu/chemical/undergrad/lab_manuals/flotation.pdf
 
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  • #3
Negative Activation is only an apparent effect, it is not a real quantity. Very rarely, in reactions that go through some kind of intermediate, the reaction rate is found to be dependent on the equilibrium constant of the rate determining step. If this step is exothermic, the equilibrium constant decreases with increasing temperature. So, even though the rate constant increases with increasing temperature (as it should - this is a sign of positive activation energy), the product of the rate constant and equilibrium constant (or apparent rate constant) may be decreasing with increasing temperature. This is what is referred to as negative activation.

The oxidation of NO to give NO2 is such a reaction.

See : http://www.rod.beavon.clara.net/nitrogenmonoxide.htm
 
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1. What is froth flotation?

Froth flotation is a method used to separate particles based on their surface properties. It involves adding certain chemicals to a mixture, which causes the particles to adhere to bubbles and rise to the surface, forming a froth layer. The froth can then be collected and the particles can be separated from it.

2. How does froth flotation work?

In froth flotation, a mixture is first conditioned with chemicals called “collectors” and “frothers”. The collectors attach to the surface of the desired particles, while the frothers create a stable foam. Air bubbles are then introduced into the mixture, causing the particles to adhere to the bubbles and rise to the surface. The froth layer can then be skimmed off and the particles can be separated from it.

3. What is the negative energy of activation in froth flotation?

The negative energy of activation in froth flotation is the minimum amount of energy required to initiate the separation process. In other words, it is the minimum energy needed to break the bonds between the particles and the liquid, allowing the particles to adhere to the air bubbles and form the froth layer.

4. What factors can affect the efficiency of froth flotation?

Several factors can affect the efficiency of froth flotation, including the type and concentration of collectors and frothers used, the size and shape of the particles, the pH of the mixture, and the speed and intensity of the agitation. The presence of impurities, temperature, and the type of equipment used can also play a role.

5. What are some applications of froth flotation?

Froth flotation is commonly used in the mining industry to separate valuable minerals from ores. It is also used in the paper and pulp industry to remove ink and other contaminants from recycled paper. Additionally, froth flotation has applications in wastewater treatment, oil and gas production, and even in the food and beverage industry for clarification and separation purposes.

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