NI 43-101 Technical Report — La Blache Fe-Ti-V Project

This report describes the proposed hydrometallurgical processing route for the La Blache Fe-Ti-V project, based on a preliminary economic assessment completed in December 2011.

Report context

The December 2011 Preliminary Economic Assessment (PEA) for the La Blache Fe-Ti-V Project outlines a staged implementation of processing plant modules for the recovery of titanium dioxide, iron oxide, and vanadium products. The concept is based on a pre-commercial demonstration plant with a nominal capacity of 15,000 tpy TiO₂, followed by the construction of three 60,000 tpy TiO₂ modules, culminating in an overall production capacity of 195,000 tpy TiO₂ over a six-year ramp-up phase and an assumed 25-year project life.

Processing route

Feed Preparation and Transport

At the mine site, run-of-mine (RoM) ore is crushed using a mobile jaw crusher, supplemented with a rock breaker and front-end loader. The crushed ore is transported by 40-tonne trucks with 20-tonne pups (“B-trains”) over a distance of roughly 120 km to Baie-Comeau, where a stockpile is maintained for ship-loading. Crushed RoM is then transported by self-unloading barges of approximately 25,000 dwt capacity to the Bécancour Waterfront and Industrial Park. At Bécancour, the feed material is transferred by truck to a stockpile at the TiO₂ Industrial Plant.

Secondary crushing and grinding are performed using a high pressure grinding roll (HPGR) circuit that reduces ore to a nominal 100% passing 1 mm, followed by a ball mill circuit producing a product with 80% passing 75 µm. A dry process was initially envisaged to reduce water inputs, though dusting may require a dust collection system or adoption of a wet grinding approach. An alternative combining crushing and grinding in one technology, as used in the cement industry, is to be investigated during the pre-feasibility study.

Leaching

The ground feed material is fed to a two-stage leaching circuit. In the primary leaching step, the ore is reacted with a 5.2 N HCl acid-brine solution at 70 °C with a 2-hour residence time. Depending on plant size (15,000 versus 60,000 tpy TiO₂), either two or three reactors operated in series are envisioned. Leaching is deliberately not carried out at higher temperatures to avoid premature thermal hydrolysis of titanium, which would precipitate titanium as an impure product.

The Stage 1 leach slurry is pumped to a thickener to settle solids, with underflow pumped through a filter press to recover leach residue. These solids feed a secondary leaching step (Stage 2), which operates under slightly more aggressive conditions (5.8 N) but still at 70 °C and atmospheric pressure. The leach residue, representing approximately 15% of the original feed volume, is collected, washed to remove residual chloride and acid, and trucked to a non-hazardous waste landfill site.

The leach circuit is fed at a rate of 11.4 tpd of ore for the pre-commercial plant. Table 17.2 in the report presents overall process design criteria, including head grades of 11% Ti, 42% Fe, and 0.25% V, with recoveries of 87% Ti, 90% Fe, and 90% V.

Solvent Extraction

The pregnant leach solution (PLS) is processed through successive solvent extraction (SX) steps using conventional mixer-settler technology. The process includes iron solvent extraction, titanium solvent extraction, and vanadium solvent extraction, utilizing organic extractants to selectively load metal species.

Iron is co-extracted in both ferrous and ferric chloride forms in the first SX operation. Some titanium is co-loaded and must be scrubbed in a separate stage prior to stripping. The iron strip solution contains approximately 68 gpl Fe and is subjected to pyrohydrolysis to recover iron oxide and regenerate hydrochloric acid.

The iron-depleted leach solution, containing approximately 14 gpl Ti and 5.5 gpl V, undergoes titanium solvent extraction. Titanium is preferentially loaded from the brine using an organic extractant, then scrubbed and stripped using a hydrochloric acid solution. The titanium-rich strip solution containing approximately 35 gpl Ti and 2 N HCl feeds the titanium processing circuit.

Vanadium is recovered from a bleed stream from the main hydrometallurgical circuit. The bleed is necessary to maintain a balance of MgCl₂, eliminate salts such as CaCl₂ and AlCl₃, and remove deleterious minor elements. Based on magnesium inputs from the leaching of La Blache RoM, a bleed of 3.5 to 5% of the overall circulating volume is anticipated, with 95% of the brine continually recirculated. This allows vanadium to build in the main brine loop, and the bleed stream is expected to contain vanadium levels of approximately 5.5 g/L based on METSIM mass balance analysis.

Iron Processing

The iron chloride solution from iron solvent extraction is concentrated by evaporation from approximately 68 gpl to 140 gpl iron, with condensate recycled as process water. The concentrated solution is processed using a spray-roaster type pyrohydrolysis unit to convert iron chloride into hematite (Fe₂O₃) powder, regenerating hydrochloric acid in the process. Natural gas provides the necessary heat, with the spray roasting process operating at an internal temperature of around 600 °C and an exhaust temperature of approximately 400 °C. The off-gas passes through a hot gas cyclone, venturi scrubber, and absorber tower to recover HCl(g). Thermal energy requirements of 3000 kJ/L of feed solution have been calculated using METSIM.

For the 15,000 tpy TiO₂ plant, 6.2 tph of iron oxide powder will be recovered (80.2 tph for the 195,000 tpy operation), feeding a storage silo that supplies a briquetting operation. The iron oxide powder is mixed with a binding agent and water, then agglomerated to produce a marketable lump ore product.

Titanium Processing

The titanium strip solution is subjected to thermal hydrolysis in a lightly-agitated tank using steam heating to 90-100 °C. This hydrolyzes TiOCl₂ to hydrated titanium dioxide (TiO₂·H₂O). Any residual vanadium transferred to the raffinate is not hydrolyzed, providing second-stage purification. Thermal hydrolysis is assumed to be carried out in batches.

Following filtration and washing, the TiO₂·H₂O slurry is fed to a rotary kiln operated at 900 °C, which drives off moisture and bound water and converts the product to synthetic rutile with an acicular (tetragonal crystal) form. The solids are then cooled and fed to a micronizing unit.

Micronizing

Synthetic rutile is micronized using a jet mill to a nominal particle size of 250 nanometers. Jet mills use particle-to-particle impact, with energy imparted through superheated steam or compressed air, and are required to break up the material before the coating section.

Surface Treatment

The ground synthetic rutile requires coating with sodium silicate and alumina to produce a marketable pigment product. These coatings are applied in a wet process in succession, imparting characteristics specific to client requirements. The coated product is recovered by filtration and transferred to a drying operation.

Drying and Finishing

The coated product is dried a second time using an indirectly-heated rotary kiln at 200 °C, then transferred to a day bin feeding a second micronizing unit to break up the coated product. The finished product is pneumatically conveyed to an enclosed storage silo equipped with a baghouse.

Packaging and Handling

The product is bagged in 25 kg paper bags, stacked onto pallets (40 per pallet), wrapped with cellophane, and loaded onto trucks or railcars. The product is also available in bulk quantities in 1000 kg intermediate bulk containers (IBCs or "supersacks") placed one per shipping pallet. Production rates are anticipated at approximately 45 kg/h for the 15,000 tpy plant and 600 kg/h for the 195,000 tpy operation.

Vanadium Processing

The vanadium bleed stream is processed through a dedicated SX circuit. The loaded organic is stripped using 1.5 N NH₄Cl solution, into which vanadium is transferred. The vanadium-rich strip solution is neutralized with ammonium hydroxide to recover ammonium metavanadate (NH₄VO₃). The precipitate is filtered, washed with cold NH₄OH solution, dried, and cooled using two hollow-flight screw conveyors in series, discharging into poly-lined steel drums.

The ammonium metavanadate crystals can be fed to a small rotary kiln at 400-500 °C, removing ammonia gas to produce technical-grade V₂O₅ powder. A fused V₂O₅ flake product can also be produced by melting, though no allowance was made for this product. The ammonia gas by-product is scrubbed at the kiln exit; recovery and re-use was assumed in the PEA, though scrubbing with sulphuric acid to produce ammonium sulphate as a potential fertilizer by-product was not considered in the study.

Acid Recovery

Hydrochloric acid is recovered through three mechanisms: iron pyrohydrolysis, titanium dioxide hydrolysis, and magnesium chloride pyrohydrolysis. The regenerated acid-brine solution is targeted to contain 6 N HCl and 225 g/L MgCl₂.

The acid-brine solution from iron pyrohydrolysis is combined with other process streams, including evaporated titanium hydrolysis filtrate and acid recovered from pyrohydrolysis of the process bleed stream. Pyrohydrolysis of magnesium chloride occurs at 800 °C, generating magnesium oxide (MgO) particles and liberating HCl(g), with a similar gas handling train to iron pyrohydrolysis including hot gas cyclone, venturi scrubber, and absorption tower. In the PEA, MgO is assumed to be shipped to a non-hazardous landfill, though the possibility of marketing is noted.

Water Management

Water is used in many parts of the process and must be largely segregated from the circulating brine to minimize dilution. Relatively clean water containing some HCl is generated from iron chloride pre-concentration and evaporation/concentration of titanium hydrolysis filtrate, collected in a centralized tank. Water used in solvent extraction stripping operations comes from the clean process water tank, partially completing a closed loop. The process requires a net input of fresh water as water vapour exits through pyrohydrolysis.

Wash water from solvent extraction operations circulates in closed loops, segregated from both brine and clean water circuits. Any wash water bleed is transferred to a wash water treatment plant (WWTP) with a skimmer tank for solvent removal. An allowance for a neutralization plant to precipitate metals by pH adjustment is included, though scrubbing solutions are envisioned to operate in closed loops, with bleed potentially returned to the leach circuit.

De-mineralized water is needed for the boiler and has been recommended for washing the hydrated-TiO₂ precipitate to reduce product contamination.

Utilities

Process water for the plant is provided by the Bécancour Waterfront Industrial Park. Potable water is supplied by the town of Bécancour fresh water treatment plant, with reservoirs of 15,910 m³ total capacity, supplemented by an additional 5,600 m³ reservoir built by the industrial park. An allowance for a de-mineralized water package has been made. Low and medium-pressure steam is available from a 550 MW co-generation plant owned by TransCanada Québec in the industrial park, though an allowance for a package boiler has been made. Allowances for compressed air and instrument air packages have also been included.

Reagents

Hydrochloric acid is available from Olin, a manufacturer of hypochlorite and hydrochloric acid at the Bécancour Waterfront and Industrial Park, with a pipeline delivering 37% HCl on demand. An allowance has been made for hydrochloric acid delivery by 32-tonne trucks as a 32% (10.1 N) HCl product, with storage capacity of 1.25 trucks representing a 40.4 m³ reservoir in a 3.5 x 4.0 m tank.

Five different organic reagents are used in the hydrometallurgical plant: three extractants, one modifier, and one diluent, delivered in 1000 kg intermediate bulk containers (IBCs). For the 15,000 tpy plant, one IBC of each extractant and three IBCs of diluent will be kept for make-up.

Magnesium oxide is received as a powder in 500 kg bags and mixed with 12 N HCl to dissolve into solution as MgCl₂ prior to addition. Ammonium chloride is delivered in 1000 kg bulk bags, with thirty or more days of reserve maintained, and dissolved to produce the 1.5 N NH₄Cl solution used in the vanadium circuit. Sodium silicate is delivered as a powder in 1000 kg bulk bags, with thirty or more days of reserve, added as a solid to the TiO₂ coating circuit. Alumina is delivered as a powder in 1000 kg bulk bags with bulk delivery allowing thirty or more days of reserve. Binding agent for agglomerate production is delivered by bulk-carrier with pneumatic transfer, dispensed in a 2% ratio with iron oxide powder. Flocculant is delivered in 700 kg bulk bags, transferred to solution using a bulk bag feeder, and mixed in an agitated tank.

Solid Waste Management

The two solid materials considered as waste in the PEA are leach residue, representing approximately 15% of the original mass of incoming feed material, and MgO generated from pyrohydrolysis of the MgCl₂ bleed stream. Both are considered non-hazardous waste for the purpose of the PEA, although the MgO may be marketable. The MgO product may also contain Al₂O₃ and non-pyrohydrolyzable salts such as CaCl₂, NaCl, and KCl, as well as other minor components dissolved from the feed material (e.g. Cr). Further evaluation is required.

Key reported parameters