Since late 2006 Oriel has continued bench-scale atmospheric test work at Mintek, South Africa, which has covered extensive tank and continuous column leaching (representing heap leaching) of the three mineral types (limonite, nontronite and saprolite) found in the Shevchenko nickel laterite ore deposit. The stirred tank leaching results carried out at solids to liquid ratio of 30% at a temperature of 90°C achieved extremely positive levels of nickel extraction of 80% to 90% in 12 to 14 hours residence time.

 

The results of these tests formed the basis for Baran’s leaching study and were incorporated into a model of the overall process flow sheet which was used to examine the technical feasibility of the circuit. The results were used to calculate reagent and utility consumptions (acid, limestone, magnesia, lime, water, fuel, gas) and these values were used in conjunction with indicative consumable costs to calculate the variable portion of the projected operating cost. Reagent and energy consumption data will be used as the inputs to the design of the continuous pilot-scale operation to commence Q1 2008 and the subsequent Phase 1 commercial-scale plant.

 

Oriel has a competitive advantage to develop a leaching operation in Kazakhstan as the Company will be supplied with sufficient sulphuric acid from Kazzinc operations in Kazakhstan. In addition, the selection of a hydrometallurgical process to unlock the value of Shevchenko ensures the project is not dependant on electrical energy costs which are expected to rise significantly in the coming years. Oriel recently completed a long term off-take agreement with Glencore to market a significant proportion of the Company’s Voskhod Chrome Project’s annual 900,000 tonnes of beneficiated chromite ore product, commencing Q3 2008.

 

Oriel has taken the decision to pursue the final testwork and construction of a commercial plant based on extensive testwork and the technical and economic assessment managed by Baran and supported by a number of experienced consultants. An agitated ambient pressure tank leach operation to produce nickel into a MHP or further into a metal is considered the most appropriate technology to unlock the potential of the Shevchenko nickel laterite. Baran, as appointed Project Managers, will immediately commence work on the process flowsheet design sufficient for local permitting to be obtained and for construction to start on site in Q2 2008 and will report back to Oriel during November 2007 on the selected plant through-put, production capacity, capital and operating cost estimates for the plant.

 

Batch and pilot scale tank leaching and nickel recovery testwork to produce both a mixed hydroxide product and metal is planned for completion by Q2 2008 and will be conducted at the South African facilities of Mintek. This testwork will confirm the design parameters for the commercial-scale plant and demonstrate the performance characteristics of the plant, based on the process flow sheet developed.

 

Tank leaching of nickel laterites is considered to be an appropriate solution to the treatment of the Shevchenko ore. Tank leaching is widely practiced in the Platinum Group Metals Industry (5 plants installed in USA, Finland, Zimbabwe and South Africa), it is fundamental to the Xstrata process (1 plant installed Australia) and is practiced by all the Central African cobalt heterogenite processes (5 plants installed, Nkana, Chambishi, Luilu, Shituru and Kabwe and 4 in design Nikanor, Tenke Fungurume, Kolwezi Tailings and Kalukundi) where the process dynamics of tank leaching are well understood.

 

During Q4 2006, in conjunction with consultants specialising in the leaching of nickel ores and heap leaching of base metals, Oriel commenced an extensive programme of test work to evaluate the potential of atmospheric leaching of the Shevchenko ore as an alternative to smelting, as suggested in the January 2006 feasibility study completed by Bateman. This test work programme followed on from very encouraging bottle roll tests which indicated nickel extraction of over 90% in approximately 30 days and with sulphuric acid consumptions that compared favourably with results presented for other nickel leaching projects.

 

In addition, encouraging beneficiation results from recent ore screening work completed in Kazakhstan by Kazmechanobr will be followed up in order to develop the most appropriate ore preparation flow sheet design that would precede the leaching stage in the Phase 1 commercial-scale plant. The upgrading tests on the ore increased the Ni grades to 1.3% Ni, which greatly improves the project economics.