Froth Flotation (Sulphide & Oxide)

Froth Flotation (Sulphide & Oxide) 2017-04-04T06:57:31+00:00
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Asbestos Fiber Rejection (8 replies)

Ace Levy
1 year ago
Ace Levy 1 year ago

Anybody with experience on Asbestos fiber rejection in copper flotation circuits. We have suffered high asbestos in our concentrate and have no solution for now.

Bob Mathias
1 year ago
Bob Mathias 1 year ago

What characterization have you completed of these fibrous (asbestos) minerals in your ore (shape, size, morphology)?

Take a look at Patra et al., 'Impact of pulp rheology on selective recovery of value minerals from ores'

Rheological behavior of mineral pulps plays a critical role in almost all mineral processing unit operations. Although the impact of rheology in unit operations such as grinding and slurry transport has received much attention in the past, this is not the case for flotation. The pathway by which the pulp rheology influences the flotation performance is not well understood. The aim of this paper is to explore how physical (shape, size and morphology) and surface chemical properties of minerals contribute to pulp rheology and pathways by which rheology can influence selective value mineral recovery and/or concentrate grade. Systematic studies involving spiking experiments (deliberate addition of fibrous minerals and other solids), measurement of pulp viscosity and yield stress, flotation tests, SEM, EDX and XRD were conducted on a Ni ore and a Cu ore. A phenomenological model was developed. The key components of the model are the formation of a macro network comprising micro-aggregates of fibrous minerals which significantly increases pulp viscosity, and as a result impedes gas dispersion and bubble-particle attachment and influence froth phase properties. Additionally, the role of various reagent types in regulating pulp rheological behavior was explored.

1 year ago
Gruppen 1 year ago

The most convenient way of rejecting fibrous material (whether it is asbestos, wood pulp, rope, or even plastic) from flotation circuits is to screen it out either before flotation or out of the concentrate using a vibrating screen. Often referred to as a trash screen ahead of flotation, or CIL/CIP circuits.

Fibrous material normally has one dimension that is larger than concentrate particles, it also adheres to screen surfaces.

If this is a real problem I would suggest you screen it out of the flotation feed, and also screen it out of the final concentrate.

You can try this in the laboratory first to see how effective it is and how much you are able to remove.

Fibrous materials in flotation feed also tend to adsorb collectors preferentially which could interfere with overall flotation circuit performance and reagent costs so getting it out before flotation may give you other benefits.

Ace Levy
1 year ago
Ace Levy 1 year ago

We do have a trash screen ahead of the circuit on our cyclone overflow with dimensions of 600/620 um.

The problem is the fiber in our ore is in very fine fraction and it causes two issues. We currently can't go coarser on the grind as we fail to float coarse copper particles in the cleaners and end up with high circulating.

It is deported in the concentrate to levels above the 0.10 limit and in the float it matts and forms networks that forces us to shut down the plant once per week for fiber clean-up of pipes and cells.

Please share more on the CIL or is it CIP you have mentioned, it sounds interesting and would be worth to try in the lab.

1 year ago
Gruppen 1 year ago

Sounds like you have an interesting (but painful) problem, shutting the plant down once a week means this is a high priority. I can't help you out with ready solutions but it is the stuff that makes us earn our salt as metallurgists, you need to (and probably already have) get stuck into it and leave no stones unturned to find a solution, the company you work for is big enough to support you in this.

Bill Rico
1 year ago
Bill Rico 1 year ago

Have you tried a dispersant to keep the fibers from forming mats such as sodium silicate? In molybdenum flotation using hydrocarbons as the collector, the moly forms ball which include gangue particles. By using the dispersant and regrind for concentrate flotation the gangue is freed and reports to tails.

1 year ago
Hauptsturm 1 year ago

You are mentioning the fibers as being asbestos. Has this fibrous mineral been positively identified as asbestos? There are a number of occupational health concerns related to asbestos and, if it is the case, then it would be wise to be very stringent with respect to managing any dust (ore, concentrate, tailing).

Since the fibers are passing through your existing 625 micron trash screen, you likely need a secondary vibratory screen at a much finer size - say about 1.5 times your P80 size.

Since the matting occurs in the cleaning circuit, it might be appropriate to locate this fine screen on the cleaner feed - so as to take advantage of the entanglement of the fibers and the resulting apparent "coarser" size.

There are a few suppliers of such fine screens - don't remember exactly the vendor.

John Koenig
1 year ago
John Koenig 1 year ago

I saw a paper at the 2012 IMPC about some research on reagents for dealing with what appears to be a very similar issue for Ni flotation. I would suggest contacting D.R. Nagaraj with Cytec based in New York.

1 year ago

I worked on a low grade Ni project for a few years where the ore was from an ultramafic deposit. We had a lot of success with a hydro cyclone used for fiber removal before the rougher float. Once the fibers got in our circuit we had issues with it building up because of our cleaner tail recirculation.

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