I have just been involved in a similar project where the upgrade was from 15% to 32%. There are a few issues i.t.o. water softening and treatment, collector choice and gangue suppression.

Could you tell us what the mineral composition of ore is? I guess magnetic separation could be "new" if your carbonate associated with (contains) some iron oxides.

Our ore doesn't have iron oxides a lot. Just about 2.5. We have 9-10% P2O5, and about 46% CaO, 13% SiO2

Combinations of Fatty acids, diesel, NaSi, and PGE give very good results. I do not think that much consideration has been given to other methods. Techniques such as gravity, magnetic etc, will not be successful as the majority of your mineral content is Ca-based. I have been involved in another sedimentary deposit and the above mentioned reagents produced excellent results.

A suppressant for carbonates.PGE = Polly Glycol Ether, not the other way round. To upgrade you P2O5 to about 32% will require that you will have to pull 75% of the gangue mass over the lip in a reverse flotation process. In a direct flotation only 25% of the mass is required to come over the lip. So, this directs flotation process. The combination of these reagents produces an excellent result. There are a few tricks in the pre-preparation phase that you will have to follow. I can help you with this with the only requirement that you give me some feedback on your results. I will guide you in preparing a process specification based on dimensionless numbers in preparation for a full scale plant design. What is the quality of your water?

In most of the papers in beneficiation of sedimentary phosphate that I road, they all suggested to float the gauges and depress phosphate. Because of that I asked you about direct or reserve flotation.

I'm using tap water.

What is the P2O5 content and gangue material content in the papers that you have studied. Are they similar? Maybe there were economic reasons for them to do reverse float. In any case, it will not be a major change from direct to reverse. Let us first concentrate on the preparation for upgrading. Have you done any grinding and particle size analysis? You must do the P2O5 content for each particle size (Range) so you can get an idea of the liberation of your feed. What facilities do you have? Is your ore the tailings from another process and if so what were the chemicals used in the primary process.

I have experience with sedimentary phosphate, now I am in similar project where the upgrade was from 10% to 30% P2O5. The flotation is reverse, float the gauges and depress phosphate with collectors for carbonates and silica.

Reverse float will work, so will direct float. It finally boils down to choice of chemicals and economics. My offer to help you to characterize your process in terms of dimensionless numbers is still standing. I will also show you how to scale-up with dimensionless numbers. And how to identify deficiencies in existing plants and how to do problem solving with dimensionless numbers.

My hypothesis is : Due to the deposit is sedimentary it seems that Gravity, Flotation, Cancination and Roasting methods must be effective to beneficiation and upgrading of phosphate.

I do not have so much experience in phosphate flotation.

My question is, if I used PGE to directly float phosphate from gangue material which is mainly composed of Calcium carbonates and Silicates, and then I can have only one stage flotation instead of two stage flotation in reverse flotation. In reverse flotation first stage, some fatty acid added to Calcium carbonates and apatite have similar surface chemistry and they float while as Silicate precipitates. In second stage a depressant is added to Caco3 and apatite where apatite gets precipitated.

If this can be done in one stage direct flotation it will have a great economic impact using PGE. Have you done some experiments on this? I know you may wonder CFD guy like me ask these questions but you may know I am interested in modeling and all these parameters are important to know.

Is the PH has an effect if we use direct flotation. 

This is quite an extended study. I will be more than willing to help and learn.

Great to hear from you again!

•Yes. The direct flotation of apatite is a "single stage” process in that it requires only one reagent dosage step and then a standard rougher, scavenger, cleaner and re-cleaner step which results in a single concentrate of about 32% P2O5.

•The reagents in this case are:

•A mixture of fatty acid , diesel and caustic soda as collector for apatite

•Sodium silicate as calcite depressant

•PGE as a pH bridge in the sense that fatty acid and apatite require about pH=7 for maximum recovery while sodium silicate and calcites require about pH >8 for maximum depressing. So without PGE one of the two processes will suffer. I believe that PGE is a sort of surface activator for both minerals.

To prove your hypothesis you will have to do some serious planning and scheduling. Has your hypothesis already been accepted by your Institution for Higher Education or are you still in the motivational stage. When do you think you will be ready to proceed with the flotation stage?

Yes you right, I have to do some serious planning and scheduling. Yes, my hypothesis already has been accepted by my Institution for higher Education.

I'm not sure, but I think about 3 or 4 weeks later I can start my flotation test.

Great suggestions! Consider reverse at pH 5.5 (constant, higher than this will float phosphates) with medium chain collectors that float carbonates (far less phosphates) together with emulsifiers, then followed by direct float with long chain collectors with depressants at higher pH as Marius suggested.

SuntecGeomet in South Africa have done a lot of work and research on these type of ores very successfully . They have all reagents required to do a good job.

He has been exposed to phosphate upgrading and has quoted suites that have been proven for over 35 years, they work well. Although PGE has been advanced by latest technologies. PGE on its own is not the reagent that will solve all your carbonate problems especially at the levels quoted. Need to treat before flotation. He is recommending the right route.

For a direct flotation, a combination of Rinkalore XP2-A ( fatty acid derived chelating collector) and fatty acid collectors has proven to reduce carbonates better relative to using fatty acids as a lead collector in the reagent suite. For reverse float, Rinkalore F8/F10 (medium chain fatty acid blend) works well. Visit http://is.gd/4JBkuM 

As a general comment, one of the golden rules in flotation separations is to float the mineral in least abundance. You have the opportunity to directly float the phosphate minerals, simplify the flowsheet and means lower capex and opex.