Detailed Process Flowsheet

Ore Preparation:

Prior to leach, ore must be dried to 1.0% moisture and oversized material milled to a D100 of 300 microns. Based on particle size distribution work undertaken on New Caledonian ore samples, approximately 10-15% of ore will require milling.

 

Extraction Plant including DNi Process™. The major areas of the DNi plant are detailed below:

• Nitric Acid Leach: Ore is leached using recycled nitric acid with minor additional makeup (overall consumption), providing high metal recoveries at atmospheric pressure and temperature (i.e. no pressure leaching required) and low specific acid consumption. This step also includes residue filtration and neutralisation with recycled MgO, with temporary dry residue storage onsite, including capture and recycle of all drainage and run-off, before being sold as engineered landfill. EKATO, global leaders in mixing and titanium tank manufacturing, have designed the complete Titanium Gr 2 reactor cascade system for nitric acid leaching;
• Iron / Aluminium Hydrolysis: Iron Hydrolysis is undertaken at elevated pressure of 6 bar and temperature of 195°C in which the leached iron is precipitated as high-grade >68% Fe hematite. This is then filtered, agglomerated and pelletised. A second stage of aluminium hydrolysis at atmospheric pressure and temperature of 180°C precipitates a mixed aluminium / iron oxidehydroxide product. Design of the Iron and Aluminium Hydrolysis plant is by KBR PLINKE with the CSIRO Carbon Steel Materials Group focusing on optimal hematite agglomeration / pelletisation characteristics using industry-standard equipment, for sale to steel manufacturers. Through the pelletisation process, the target grade of pellets to be produced is approximately 65-66% Fe.
• Strong Acid Regeneration: This step produces Strong Nitric Acid for recycle to Leach circuit. Design of this system is by KBR PLINKE, who are global experts in the concentration, purification and recovery of nitric acid.
• Hydroxide Precipitation: This step precipitates nickel and cobalt at atmospheric pressure using recycled MgO, with slurry filtration to form a dry cake for feed into the Sulfate Refinery. This is a modified process to the one used in existing sulfate-based High Pressure Acid Leach (HPAL) systems for Mixed Hydroxide Precipitate (MHP) production.
• Barren Evaporation: Once the nickel and cobalt is precipiated, magnesium nitrate remains. This step produces a recycle stream of high concentration and temperature magnesium nitrate from Hydroxide Precipitation that efficiently provides low capital heating for iron hydrolysis to occur, with a portion of this stream being bled for removal from the circuit via Thermal Decomposition (using a Fluidised Bed Reactor). Design and supply of the Barren Evaporation unit is by KBR PLINKE.
• Thermal Decomposition: A Fluidised Bed Reactor (“FBR”) is used to heat the barren magnesium nitrate solution from Primary Precipitation to 750°C, causing it to decompose into solid MgO and Nitrogen Dioxide / Nitric Acid vapour. This industry-standard technology is used in the industrial production of magnesium oxide from magnesium brines. The MgO is recovered and used within the plant, with the excess sold as high grade MgO. Design of the FBR is by the experienced Hatch Pyrometallurgy Group.
• Weak Acid Regeneration: This step captures the vapour from the FBR and produces Weak Nitric Acid for recycle to Leach circuit. Design of this system is by KBR Weatherly, a leading worldwide supplier of nitric acid production technology. They have built more than 70 of these plants around the world.

 

Sulfate Refinery:

The Sulfate Refinery utilises an industry standard treatment process to produce battery grade nickel andcobalt sulfate. Global specialists JordProxa are designing and supplying the three crystallisers. SENET are designing and supplying all three SX circuits. This Sulfate Refinery includes:

• Sulfuric Acid Releach and Aluminium Removal using Limestone: This step produces a clean high grade Ni/Co/Zn/Mn/Mg liquor stream to feed Impurity Solvent Extraction, as well as a Gypsum product for agricultural use.
• Impurity Solvent Extraction: This step uses D2EHPA, sulfuric acid and ammonia to selectively remove Mn and Zn impurities from the process.
• Cobalt Solvent Extraction / Purification: Uses Cyanex 272, sulfuric acid and ammonia to selectively remove Mg and Co, producing a high purity stream of Cobalt for crystallisation and sale as batterygrade CoSO₄.7H₂O.
• Nickel Solvent Extraction: Uses Versatic 10, sulfuric acid and ammonia to selectively remove Ni, producing a high purity stream of nickel sulfate for crystallisation and sale as battery-grade NiSO4.6H2O.
• Ammonium Sulfate Crystallisation: This step recovers the ammonia used in the Sulfate Refinery as fertiliser-grade NH4(SO4)2 (amsul) as well as smaller volumes of a liquid mixture of Ammonium Nitrate / Ammonium Sulfate, both products will be sold for agricultural use.

 

Hematite Pellet Plant:

Dried, filtered hematite from Iron Hydrolysis is mixed with various binders/additives (bentonite, coke breeze, quicklime, etc.) before being pelletised and fed into an induration furnace at 1250°C following which it is cooled and discharged ready for sale.

QPM has been in discussions with parties who have expressed interest in a  commercial arrangement regarding BOO structures for a pellet plant to secure offtake. These parties  include steel mills and trading houses.

The hematite pellets to be produced by the TECH Project have several advantages, including:

• High iron % grade and low impurities for silica and phosphorus, which for traditional DSO iron ore,  attract penalties and threshold limits; and
• The green credentials associated with QPM’s hematite pellets are attractive for the carbon steel  industry.

 

HPA Refinery:

 The HPA Refinery utilises industry standard hydrochloric acid leach and purification steps to produce 4N High Purity Alumina. QPM has a technology license arrangement with Lava Blue who provide additional “know-how” in this area. KBR are providing leaching and acid recovery design and equipment. Hatch are providing thermal processing design and equipment.

Testwork was undertaken in conjunction with Lava Blue on aluminum hydroxide produced as part of the DNi ProcessTM and also on purchased aluminum hydroxide, which has higher purity and can be readily purchased at low cost. Although both were suitable feedstocks, the testwork determined that when using purchased aluminium hydroxide, less purification steps would be required in the HPA refinery, resulting in lower capital and operating costs – especially given the synergies of being part of the overall TECH flowsheet. As a result, the Feasibility Study has adopted purchased aluminium hydroxide as the base case scenario.