Guinea-Bissau – TSX-V listed phosphate junior GB Minerals has successfully completed its phosphoric acid and diammonium phosphate (DAP) test work based on materials generated during the beneficiation pilot plant test work from its Farim phosphate project.
- Continuous phosphoric acid tests resulted in merchant grade of 50% to 52% P2O5
- Minor Element Ratio (MER) ranging between 0.045 and 0.051, significantly below the recommended limit of 0.085 for producing high-analysis fertilizers such as DAP
- CaO/P2O5 ratios contained in the Farim phosphate amongst the world’s lowest at 1.41 resulting in low sulphuric acid consumption and less phosphogypsum production, to the benefit of customers
- Successful DAP production using unclarified phosphoric acid
- Total nitrogen ranging from 18.1% to 18.6%
- Available P2O5 ranging from 18.1% to 18.6%
In the first half of 2015, KEMWorks Technology developed a beneficiation flow sheet for the Farim phosphate mine based on a QEMSCAN analysis performed by SGS Mineral Services and bench-scale beneficiation test work performed at KEMWorks’ laboratories in Lakeland, Florida.
A representative sample for the first seven years of mining was prepared for this test work. Results indicated that a 34.0% P2O5 product could be achieved by washing, scrubbing and particle sizing only, and that by adding a silica flotation step, the grade could be increased to 35.9% P2O5.
In addition, in May 2015, ALS Metallurgy in Kamloops, British Columbia processed a 1 t bulk sample to generate several grades of phosphate (from each stage of the flow sheet) for fertilizer test work. The bulk sample was also representative of the first seven years of mining.
Using various samples generated from the ALS bulk testwork, continuous phosphoric acid tests were performed on blended material ranging in grade from 30.2% P2O5 to 33.3% P2O5.
The phosphoric acid test work simulated a commercial dihydrate process at KEMWorks’ laboratories. Merchant grade phosphoric acid was produced with a range between 50% to 52% P2O5, with MER ranging from 0.045 to 0.051 for the 30.2% to 33.3% P2O5 grades, respectively (an MER of 0.085 or less is recommended to make high nitrogen analysis fertilizers such as DAP (18-46-0)).
The low acid MER from all grades tested is favourable for the production of on-specification DAP. Additionally, the material tested from the Farim project is deemed to have one of the lowest CaO/P2O5 ratios at 1.41, which appears to be lower than other rock sources and should result in less phosphogypsum production, offering a further benefit to potential customers.
DAP was chosen for testing as it is the most widely traded phosphate fertilizer globally. DAP was made in a batch process by ammoniating concentrated phosphoric acid and the product obtained from each grade exceeded commercial specifications. The DAP was produced using unclarified phosphoric acid, which demonstrates the quality of the Farim phosphate rock and the phosphoric acid produced from it, and will provide further advantages to fertilizer producers.
“The successful phosphoric acid and DAP tests clearly demonstrate the viability of the Farim project and further support our belief that the Farim phosphate deposit is one of the highest quality in the world. The benefits downstream to potential customers are even more apparent with these results. The company is in active discussions with multiple parties for key offtake agreements and we hope to start updating shareholders on these discussions,” says Luis da Silva, President and CEO.