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Installing magnetic separator before flotation (8 replies and 4 comments)

glocmines
2 weeks ago
glocmines 2 weeks ago

The ore is Copper Sulfides with liberation size of 130 um, Pyrite of 100um and Magnetite of 160. since magnetite is the coarsest, can we place the magnetic separator before flotation. Our ball mill is set to produce a P80 of 150 um in the cyclone overflow?

We also have Acid soluble copper oxide as tarnished sulfides? so we are planning to implement sulphidisation after floating the copper sulfide ores. are we doing the right thing? 

Victor Bergman
2 weeks ago
Victor Bergman 2 weeks ago

How much magnetite, pyrite and copper do you have? How much copper sulfides VS oxides? Detailes assays?

glocmines
2 weeks ago

The head grades are:0.4 Cu, 0.05 Acid Soluble -Cu oxide, 3% Fe as oxide. The Mineralogy of the Ore: Chalcopyrite, Bornite,Pyrite, Magnetiteand Cu oxides as tarnished sulfides

Jorge Ganoza
2 weeks ago
Jorge Ganoza 2 weeks ago
1 like by David

Based on the information you mentioned, I think the design should consider copper flotation and magnetite can be recovered from the copper flotation tailings. In order to design the copper flotation circuit you should analyze the CuOx/Total Cu ratio to determine the impact of the copper oxidation on the copper recovery by flotation. Sometimes, the degree of oxidation is minimum, and the design should be focused on the copper sulphides.

Copper flotation tailings can be fed to the primary magnetic separation step.  The design of the magnetic separation area should include the primary magnetic separation step, regrinding, classification by cyclones, cleaning circuit and concentrate thickening. The quality of the magnetite concentrate is very important, for that reason the magnetic rougher concentrate is reground to liberate more the magnetite.

It is important to indicate that steel makers have different considerations respect to the quality of the iron concentrate.  Many times the idea is to blend different types of iron ore concentrates to minimize the impact of impurities. As a reference the typical levels of minor elements is as follow, SiO2 <3.5%, Al2O3 <1%, Mn <0.5%, P <0.1%, S <0.1%, Cu <0.01%, and  (Na2O + K2O) <0.5%. 

glocmines
2 weeks ago

The head grades are:0.4 Cu, 0.05 Acid Soluble -Cu oxide, 3% Fe as oxide. The Mineralogy of the Ore: Chalcopyrite, Bornite,Pyrite, Magnetite And Cu oxides as tarnished sulfides

do you advise to recover the pyrite as well?

Also, from the given liberation size, magnetite is the earliest one to be liberated, immediately after the ball mill. (Ball mill P80=150, Magnetite liberation size=160). Can we recover magnetite first by magnetic separator and its tail will be subjected to flotation of copper sulfides?

what will be the difference?

Venkatesh
2 weeks ago
Venkatesh 2 weeks ago

Alternative: Can you use magnetic lining for mill if possible. Thanks

Philip Stewart
2 weeks ago
Philip Stewart 2 weeks ago

There is not enough information to answer this properly.  More mineralogical information is required.  This could be obtained either instrumentally or by lab experimentation.  In particular you need to know what the association between the copper and the magnetite is.  At the grind size you have chosen how much of the sulphide would still be associated with the magnetite?  I would choose to check this by lab experimentation by running a series of magnetic recovery tests over a range of grind sizes produced if possible from an actual or simulated continuous milling circuit rather than a simple batch grind.

The data would tell you what loss of copper occurs for any particular grind and magnetite recovery and an informed judgement could be made. 

Is pyrrhotite present?  Although only weakly magnetic it could still be a complication.

Why would you choose a grind size coarser than the liberation size of the copper sulphides?

glocmines
2 weeks ago

our feed is 78873 MTPD (3300 TPH)
Head grade(%): 0.4 Cu, 0.05 Acid Soluble-Cu oxide, 3% Fe as oxide
Specific Gravity:2.8
Mineralogy: Chalcopyrite, Bornite, Pyrite, Magnetite, Cu oxides as tarnished sulfides

We are given with the following Liberation sizes:
Cu sulfides 130 microns
Pyrite 100 microns
Magnetite 160 microns

and we are also given a ball mill with P80=150um.

Is it appropriate to install magnetic separator before, and the tails of it will go to flotation. or install flotation first and its tail will go to a magnetics separator?

if we base it on the liberation size, it is apparent that we use magnetic separation after grinding since magnetite is already liberated, but i don't know why most of the plants ive researched installed their magnetic separator after the flotation. where the feed of magnetic separator is the copper sulfide flotation tails.

Hauptsturm
2 weeks ago
Hauptsturm 2 weeks ago

The is a copper (chalcopyrite, bornite) flotation plant only. Forget the Cu oxide and magnetite. If your definition of liberation is correct and if you ran some flotation tests you'd see the Chalcopyrite, Bornite recovery OK at the 150 um you have. 

  • Did you run laboratory tests?
  • What is your definition of liberation size? 
  • Can you post your liberation data here?
glocmines
2 weeks ago

tbh sir, we are trying to design a plant that would treat the ore:

our feed is 78873 MTPD (3300 TPH)
Head grade(%): 0.4 Cu, 0.05 Acid Soluble-Cu oxide, 3% Fe as oxide
Specific Gravity:2.8
Mineralogy: Chalcopyrite, Bornite, Pyrite, Magnetite, Cu oxides as tarnished sulfides

We are given with the following Liberation sizes:
Cu sulfides 130 microns
Pyrite 100 microns
Magnetite 160 microns

and we are also given a ball mill with P80=150um.

Jorge Ganoza
2 weeks ago
Jorge Ganoza 2 weeks ago

Your information confirms that your design should be focused on the copper recovery. It  means to produce a copper concentrate. Try to recover copper oxides is not a good idea, the CuOx grade is very low. Now regarding the magnetite recovery, I can see the total iron grade is low, it would be very challenging try to produce a marketable iron concentrate. The idea is try to recover iron from copper flotation tailings.

It is important to perform a complete testing program to evaluate the potential recovery of magnetite. The testing program can evaluate several things such regrind the copper flotation tailings, it would be possible to find an optimum point. Normally, it is not necessary to regrind the copper flotation tailings, but you could evaluate if there is any benefit or not. If the iron recovery in the rougher stage is good, the main problem is to clean the iron rougher concentrate, the testing program should evaluate the iron concentrate quality. One of the problems is the presence of non-sulphide gangue minerals.

If you try to concentrate the magnetite first, your rougher concentrate would be contaminated with non-liberated particles. It would not be possible to get a nice iron concentrate. Also, your copper recovery would be affected.

Pyrite could be separated for two reasons, first the ore contents auriferous pyrite (you did not mention if the ore contents gold); second, if the magnetite recovery and concentrate quality is improved, the pyrite should removed. Normally, the pyrite should be reported in the tailings. As you can see try to separate pyrite needs a special study.

It is important to design the grinding circuit. In order to do this, it is necessary to perform a grindability testing program (i.e. SMC, PLT, UCS, SPI, JKDWT, BRWI, BBWI, Ai). Results from the Bond Ball Mill Work Index (BBWI) tests are important. Ore hardness is necessary to design the grinding circuit. 

As you can see the testing program is important to design the process plant and determine the metallurgical performance.

Hauptsturm
2 weeks ago
Hauptsturm 2 weeks ago

Did you run laboratory tests?

Khosana
1 week ago
Khosana 1 week ago

Usually one would go for float first and then followed by magseps. Put it magseps prior to float might compromise your Cu recovery.

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