a new processing algorithm

7/27/2019 A New Processing Algorithm

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Since 2004, the author has implemented the algorithm that the performance of a processing

plant comprises:

equipment performance operators competence, and mining chemicals used

Give credit to our maintenance colleagues, equipment invariably operates at 95+%

efficiency! The only room for improvement lies in the settings of flotation cells in terms of

parameters such as submergence and operational speed and direction (Figure1). These are

all cosmetic and can be rectified in three hours.

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Operators competence in countries like Zambia and DR Congo is between 50 and 75%. The

drawback being older supervisors reluctance to pass on experience and knowledge to the

younger workforce, for fear of losing their jobs! A concerted effort is needed in this area is

international standards are to be met. A well trained labour force will make the supervisor

look competent anyway, as he is the one who interacts with management and is the

recipient of the praise, or criticism?


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The field of mining chemicals leaves a lot to be desired. We are all aware of the huge sums

of money spent on research and development of new mining chemicals by the

manufacturers. They fund research at their own laboratories, at university research

facilities and at independent laboratories. This is in addition to providing testing reagents to

mines free of cost, or at best, at reduced cost. Does industry endeavour to make use of suchresearch? I fear not!

Consider the simple concept of reagent addition to a flotation circuit. Because a conditioner

is installed at the head of the flotation circuit, 80-90% of plant operators add all of the

reagents to that conditioner. This concept is archaic and it is what we were taught at

university 40 years ago! The modern concept is staged addition. By adding all of the

collectors to the conditioner, a thick, scummy and uncontrollable froth is obtained which

yields a low grade concentrate. Often, because of the entrained insoluble minerals in such

concentrate, it is unmarketable. This could have severe cash flow implications on thebusiness unit (Figure 2).

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An approach the author has adopted since 1987 has been the staged addition of collector.

The rationale being:


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During the milling process, minerals which are naturally hydrophobic will easily andreadily float when fed to a flotation cell. To take advantage of this phenomenon, a

starvation dosage of collector, say 30% of total, is added at the head of the

flotation circuit.

In the middle of the circuit, where the bulk of the floatable and liberated minerals,need to be recovered, add the bulk of the reagents, say 55% of total.

Towards the tail end of the circuit, just add an insurance dosage, say 15% of total.This is compounded by the fact that the preceding flotation cells have been acting as

conditioners/reactors in series. The ensuing reagent profile will be as shown in

Figure 3.

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By implementing this methodology, a high grade product which is low in insoluble minerals

is obtained (Figure 4). Such product is much sought after by smelters to be used as a

sweetener for more refractory concentrates.

0

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Addition point

Reagent addition in a flotation bank


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Due to their inherent natural floatability, knowing the way sulphide minerals segregate in a

froth column (Figure 5) helps to:

Produce a cleaner concentrate Reduce reagent cost, and Enhances total metal recovery

Although known by plant operators, they often overlook this basic principle. Even graduate

metallurgists, they studied such phenomenon as the flotation rate constant (k), hardly

pay attention to such natural segregation.


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Reagent manufacturers offer:

Promoters Collectors Depressants, and Frothers

All aimed to make this important task, easier and more manageable.

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Ramoutar (Ken) Seecharran

Consultant

a new processing algorithm

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