Hydrometallurgy of Platinum Ore
Investigation of the Process of Hydrometallurgical Processing of Platinum Ore Concentrates
Tech Area / Field
- MAN-MCH/Machinery and Tools/Manufacturing Technology
- CHE-IND/Industrial Chemistry and Chemical Process Engineering/Chemistry
8 Project completed
Senior Project Manager
Tyurin I A
VNIIKhT (Chemical Technology), Russia, Moscow
- State Research Institute of Organic Chemistry and Technology, Russia, Moscow\nJoint Stock Company Institute Gipronickel, Russia, St Petersburg
- University of Pennsylvania Medical Center, USA, PA, Philadelphia\nForschungszentrum Karlsruhe Technik und Umwelt / Institut für Technische Chemie, Germany, Karlsruhe
Project summaryThis Project is directed to development of alternative, ecologically safe, low-level-waste technology for processing of platinum ore, that will allow to draw into processing concentrates of platinum metals (PM) from ore deposits practically non-exploited now.
Technologies for processing of platinum ore concentrates, now existing all over the world, include the following main processes:
1. Smelting of concentrate, containing 30-50% non-ferrous metals and 100-500 g/l platinum metals (PM), to obtain slag and matte.
2. Oxidative smelting of the matte (converting) to obtain converter matte free of iron.
3. Leaching of non-ferrous metals from the converter matte followed by their electrorefining.
4. Leaching of PM from residues after the first leaching or isolation of PM as slurries while electrorefining non-ferrous metals. Here they obtain concentrates with 10-50% PM that are given to refineries.
5. Separation and purification of PM from non-ferrous metals, partition of PM that takes place at refineries. To obtain PM, they apply hydrochlorination of the concentrate, precipitation of complex PM salts, ion-exchange processes.
The aforesaid technology requires smelting of large concentrate quantities at ~1500°C, I. e. it is power-intensive. It requires high capital costs and environmental costs. Besides, some part of platinum ore cannot be practically processed independently with that technology be practically processed indepently with that technology. These are ores, containing appreciable quantities of chromium oxide that are widely spread in the world. E.g. in South Africa, platinum reserves of the reef, where at present more than 60% of world platinum are mining, unfitness smelting for chromium containing ores is bound up with property of chromium oxide to promote overgrowing surfaces during smelting. Therefore chromium-containing concentrates are processed in very little quantities and are blended with the concentrates from Merensky reef.
The objective of this Project is to create a complex of hydrometallurgical processes for recovery and refining of ore platinum. The complex includes new approaches to successive leaching it from non-ferrous metals concentrates with mineral acids and oxidativeleaching from PM residues with hydrochloric acid. The active use of new ion-exchange materials to extract PM from hydrochloric acid solutions and non-ferrous metals from mineral acids solutions is a distinctive feature of processes under development.
In particular, after 2.5 years of scientifical and experience-construction work of specialists of SRIOChT and Priokski factory of non-ferrous metals (PFNM) (Kasimov) in winter 1995/96 years on PFNM was organized production of Pt and Pd from concentrates of Pt-ferrous sand and departures production of gold and silver. In production were used resin and solvent extraction. In 1997 production of platinum on factory (PFNM) has exceeded 5 tons. Value of production of platinum less than on Krasnojarsk factory of non-ferrous metals.
At a same time in the course of realization of ISTC Project N 106, ion-exchange materials were tested, synthesized from chemical agents, intermediate products of their synthesis and detoxification. They allow to extract platinum and palladium from solutions with complex salt composition together with their separate desorption (nitrogen and sulphur containing materials); to separate effectively platinum from palladium and other PM by liquid extraction (oxyamines, oxysulfides); to extract effectively cobalt and copper from chloride solutions separating them from nickel and non-ferrous metals (oxyamines). Besides, it was shown, that with use of chemical agents as raw materials, analogues of practically all ion-exchange materials, applied in hydrometallurgy of PM at present, can be obtained 9 amines, sulfides, phosphates and phospine oxides).
Using of these ion-exchange materials side by side with the known ones (or their analogues) will allow to solve a task of PM extraction from leaching solutions of concentrates and separation of platinum, palladium and other PM as well as purification of associated non-ferrous metals. Platinum and palladium are disorbed from saturated ion exchanger with mineral reagents. Inpidual salts of platinum and palladium with purity 97-99% of the main substance are precipitated from the desorbates. After single recrystallization or liquid extraction, refined platinum and palladium salts are obtained, that are calcinated to form sponge, the sponge is smelted to indots. Other PM (if any) are sorbed with other ion exchanger.
All the technology, from concentrates up to platinum and palladium indots, can be performed at one plant. Only concentrate of other PM (rhodium, iridium, ruthenium), containing no non-ferrous metals, will be directed to a refinery.
Thus, the processes under development will allow avoiding costs for pyrometallurgy (power requirements for smelting are about 600$ per a kilogram of platinum), to halve production cycle of refining (300-500$ per 1 kilogram of platinum) and finally to involve a new type of platinum raw material in production. Economic efficiency of the latter can sparsely be exaggerated. After elimination of pyrometallugical operations, environmental loading and correspondingly environmental control costs will be considerably reduced.
The process under development must provide inpidual leaching of nickel, cobalt, copper from the concentrate to solutions suitable for refining of these metals; isolation of iron from residues after leaching; practically total (more than 99%) leaching of PM; recycle of applied solutions. In this case, solutions of non-ferrous metals in addition should be purified from metal impurities. It is necessary to provide PM extraction to the same solution (i.e., exclude spreading of PM in technological products). The solution should not contain large quantities of trivalent iron (less than 10 g /1). Extraction of PM with a solvent from the solution also exceed 99% and their residual content in solutions should not exceed 1 mg /1.
Realization if this task, taking into account works already done, will require about 2 years and a team of workers, 37 in number, including technologists, specialists in synthesis of ion-exchange materials, analysts, laboratory assistants. Taking into consideration complexity and specificity of this task, the Project seems to be realized by cooperation of three institutions: ARRICT, institute that has a great experience in the field of synthesis and application of ion-exchange materials in PM technologies; JSC "Institute Gipronickel" that is a leading scientific institution of Russian Joint Stock Company "Norilsky Nickel"; and SRIOChT, that is a leading institute in the field of warfare chemical agents.
Finally, treatment and generalization of the Project results will result in selection of the most efficient method of processing platinum ore concentrates to obtain refined platinum and palladium salts as well as concentrate of associated metals. Before the completion of this Project, we want to carry out marketing investigations to find a customer, who can finance research and development works on the processes.
The permanent increase of platinum consumption all over the world for the latest years (from 3,320 thousands ounces in 1S87 up to 4,880 thousands ounces in 1996), and sharp increase of palladium consumption (from 3,185 thousands ounces up to 6150 thousands ounces for the same time), actual prohibition of construction of new pyrometallurgical productions for processing of PM concentrates in most countries (because of their environmental hazard), as well as replacement of ion-exchange materials, whose synthesis is problematic or very expensive because of deficiency of raw materials, by those synthesized from chemical agents, precursors and destruction products, all this makes the Project actual.
Results to be expected
The result of the Project realization will be development of low-waste-level, ecologically safe processes of hydrometallurgica, processing of platinum ore concentrates, including those from chromium containing ore deposit UG-2 This development will use ion-exchange materials, including those synthesized from chemical agents and their semi-products. The final products will be pure ammonium chlor&platinate and dichlorodiaminopalladium salts and concentrates of associated metals, containing less than 10% non-ferrous metals, as well as pure solutions of non-ferrous metals suitable for their classic extraction as salts or by electrorefining.