Date: Aug 15, 2018
August 14, 2018 (Source) — Prophecy Development Corp. (“Prophecy” or the “Company”) (TSX:PCY, OTCQX:PRPCF, Frankfurt:1P2N) is pleased to announce the results from the metallurgical tests conducted by Northwest Nonferrous Metals Mining Group Co., Ltd. (“NWME”) on samples collected from the Company’s Gibellini Vanadium Project (the “Project”). Samples were collected by NWME’s technical team during their visit to the Project’s site in February 2018, with tests performed at NWME’s facility in Xian, China.
98.6% V2O5 Produced on the 1st Run with Simple Conventional Flowsheet
NWME used solvent extraction (“SX”) processing method to recover vanadium from sulfuric acid pregnant leach solution (“PLS”) generated by bottle roll and column test acid leaching on Gibellini samples. The solution was reduced and then precipitated using ammonia to make ammonium metavanadate (“AMV”). The AMV was calcined and heated then cooled and pulverized. A vanadium pentoxide with 98.56 % purity content was produced. The assay for this work is shown below:
| Gibellini vanadium pentoxide assay | |||||||||
| V2O5 % | SI % | Fe % | P % | S % | As % | Na2O % | K2O % | Al % | U % |
| 98.56 | 0.0078 | 0.88 | 0.058 | 0.47 | 0.0026 | 0.43 | 0.052 | 0.22 | 0.0001 |
Uranium content is less than 0.0001% which does not affect the marketability of the product.
The PLS was produced with very low deleterious elements which enabled using an efficient SX process. The PLS V2O5 concentration was 1.15 gram per liter and the Pregnant Strip Solution V2O5 concentration was 39.61 grams per liter.
Overall Vanadium Recovery of Over 60% and Low Acid Consumption
PLS was produced from both bottle roll and column tests. Sulfuric acid was added to the feed material with the bottle rolling for 1 hour, then the open bottle was allowed to cure for 24 hours and water was added to the bottle to attain the desired density (40%). Initial samples were taken at 6 hours, 12 hours, 24 hours, 36 hours, 48 hours and then once a day until the bottle roll was completed.
In column tests, sulfuric acid was added to the feed material and the material was allowed to cure for 24 hours before initiating the leaching. Leaching was conducted by applying 108 grams per liter acid solution over the material. PLS was collected every 24 hours and samples were taken for vanadium analysis. All the tests were performed at room temperature and at atmospheric pressure.
The results of the tests are given below:
| Test | Leach Time | Vanadium Recovery % | Sulfuric Acid Consumed kg/t |
| Column Test | 21 days | 70.74 | 100 |
| Bottle Roll Test – investigate the effect of the curing method and increase of sulfuric acid addition on the vanadium recovery | 50 hours | 62.8 | 150 |
| Bottle Roll Test – investigate addition of NWME prepared leaching agent on the vanadium recovery | 144 hours | 66.5 | 100 |
| Bottle Roll Test – investigate the leaching of coarse feed (2mm) on the vanadium recovery | 216 hours | 63.7 | 100 |
The results of the bottle roll and column leach tests performed by NWME largely validate the results of previous tests performed by McClelland Laboratories on Gibellini bulk sample in 2013 (18 tons of material).
