Laboratory test work is vital to validate or provide new information for process design. Combined with conceptual flowsheeting development it allows validation of processes. Our fully equipped laboratory conducts test work on real or synthetic liquors - some examples are:

• Lithium hydroxide crystallisation from traditional spodumene metallurgical/electrolysis/soda ash leach route.
• Lithium hydroxide monohydrate crystallisation from alternative solvent extraction upstream processes.
• Lithium chloride to battery-grade lithium carbonate conversion.
• Nickel sulphate hexahydrate crystallisation.
• Cobalt sulphate heptahydrate crystallisation.
• Manganese sulphate monohydrate crystallisation.
• Lithium bleed recovery using carbonation step incorporating varying chemistries.
• Lithium carbonation crystallisation.
• Lithium chloride evaporation.
• Rare Earths Evaporation - multiple and individual elements.
• Effluent treatment and multiple zero liquid discharge (ZLD) applications.
• Many more.

Impala Platinum BMR generates various effluent streams and required an effluent treatment plant (ETP) to dispose of current effluent dam contents, plus handle future effluent arisings. This project entailed the design and supply of an effluent crystalliser designed to treat the holding dam contents, acting as a zero liquid discharge plant from which salts will be produced as a mixed, damp crystal for disposal to waste site.

Effluent water from the Sasol Secunda Nitro Fertiliser site was previously stored in existing dams and distributed into the farming community. This outlet became unavailable, and the customer required a plant to sufficiently concentrate the effluent, allowing for economic disposal, while producing clean water. The primary dissolved salt in the effluent water is ammonium nitrate. A reverse osmosis (RO) plant coupled with a triple effect thermal evaporation plant was selected to produce a concentrate of which 60% is ammonium nitrate.

Three stages of concentration are used to achieve the total evaporation rate: first effect, second effect and third effect. The required energy in the first effect is provided by thermocompression, using steam as the motive fluid combined with part of the vapour produced in the first effect. The remainder of the vapour from the first effect is routed to the second effect heater. Each subsequent effect operates at a lower pressure and temperature than the previous effect; thus vapour produced in each effect is used to drive the evaporation process in the following effect.

Any solids formed are removed from the product concentrate via a filter press. A final flash cooling stage is included upstream of the filter press to ensure maximum solids precipitation to avoid solids in the final concentrated product.

The resulting condensate is treated in the RO plant, providing the customer with a clean water source.

The aim of the project was to provide Mpact with a sustainable, waste ash treatment program producing a pure dry Sodium Sulphate product from which value could be realised. The plant also produces a Zero Liquid Discharge (ZLD) solid mixed salt and a filter cake requiring disposal. The latter in an existing low cost dump, and the mixed salts in a class HH disposal facility. The plant also generates very clean process condensate which is of a quality where it could be reused as boiler feed water, discharged into the river, or finally reused in the process, reducing the makeup water requirements to near zero.

Pretreatment is required to remove insolubles by filtration and converting other impurities as possible. Oxidation by peroxide follows in a four stage reactor system then acidification of converted sulphites to sulphates.

The resulting liquor is fed to the crystalliser plant, which consists of a single forced circulation crystalliser with a draft tube type design.

Crystals are formed by evaporating the solution to form a slurry, from which solids are then separated for processing. A two stage Mechanical Vapour Recompression (MVR) Fan set is used to recompress the vapour resulting from boiling of the liquor. This vapour is then used as the heating medium which drives the evaporation process, resulting in a highly energy efficient design. A hydrocyclone, pusher centrifuge and a screw conveyor facilitate the separation of the solids from the slurry which is then fed to a rotary dryer and conveyed into a storage silo.

A small purge from the sodium sulphate crystalliser is incorporated to ensure the desired purity of crystals is obtained. This purge is fed to a small steam operated ZLD crystalliser to convert the purge into a damp cake for disposal.

The equipment was supplied in corrosion resistant materials such as super duplex stainless steel, fibre-reinforced plastic and titanium.

JordProxa Africa built a novel crystallisation facility to address a process requirement of SAPPI to reduce targeted chemical content in some of their process streams.

The source of the effluent is three effluent streams; Ash leach solids, the Chlorine Dioxide scrubber purge, and the Chlorine Dioxide plant waste sulphuric acid.

The objective of the plant is to recover the maximum crystalline mass for recycling back to the digesters, whilst maximising the purge of chlorides and potassium in a damp solid waste product (crystals) for disposal into a registered hazardous landfill site. Water is also recovered at a high specification.

A three stage process was designed and installed, with the first stage comprising a pre-treatment section where the carbonates are removed through acidification and de-aeration.

The second stage comprises the main crystalliser generating a sodium sulphate crystalline product containing small quantities of potassium with chloride content minimized. The solids from the first stage were slurried in a Black Liquor stream for transport back to the digesters.

The third stage of the plant was a small ZLD crystalliser.

In this instance, the client’s feed was a concentrated nickel sulphate catholyte stream. The feed also contained significant levels of impurities, such as iron, chlorides and free sulphuric acid. The crystalliser is operated under vacuum in order to produce the desired α-hexahydrate crystals.

The entire plant was constructed out of SAF2205 and titanium to resist the effect of chlorides at the low pH and high temperatures experienced in the plant. The crystals from the crystalliser are dried in a fluid bed dryer and the final product is bagged in 1 ton bags.

Special design features include a compact layout incorporating a single body forced circulation crystalliser, two off pusher centrifuges and a circular fluidised bed type dryer. The dryer off-gas scrubber comprises a two stage design to reduce final gas contamination levels to well within the desired specification.

JordProxa Africa were the successful bidders for the design and supply of equipment for a complete effluent treatment project in Chile. The aim of the project was to provide the customer with a sustainable, Zero Liquid Discharge (ZLD) effluent treatment program, producing solid mixed salt and sludge for disposal and clean process condensate for re-use within their process.

The pre-treatment section is required in order to remove metals and other impurities, leaving a mixed brine solution that can be evaporated to yield a mixed salt crystal. The cleaned liquor is fed to a single forced circulation crystalliser where crystals are formed by evaporating the solution, making a slurry from which the crystals are separated for disposal. The plant incorporates a two stage Mechanical Vapour Recompression (MVR) Fan set for energy efficiency. Hydrocyclones and screen-scroll centrifuges followed by screw conveyors complete the solids separation process.

The liquor is high in chloride ions necessitating the construction of equipment in corrosion resistant materials such as super duplex stainless steel, fibre-reinforced plastics (FRP) and titanium.

Cold feed is heated by falling film evaporator (FFE) concentrate and FFE process condensate to near boiling before being de-aerated to reduce scaling. Hot, de-aerated feed is concentrated in a mechanical vapour recompression (MVR) driven falling film to improve the efficiency of cooling crystallisation yield.

The concentrate is flash cooled to maintain energy efficiency and limit the energy removal required by refrigeration in the surface cooling crystalliser where large Glaubers crystals are grown at near 0^oC. Glaubers crystals are dewatered in a centrifuge and further impurities continuously washed off the cake - these crystals are continuously discharged via screw conveyor into a melting vessel.

Glaubers salt melts into itself and process condensate can be added to assist dissolution, forming the pure solution feed to the anhydrous sodium sulphate (SSA) forced circulation crystalliser, which is driven by MVR in the form of two state-of-the-art high speed turbo fans. SSA crystals are grown in a draft tube forced circulation crystalliser and continuously extracted and dewatered and washed by centrifuge.

Detergent grade SSA damp crystals are continuously discharged into a rotary dryer where they are dried to specification before being pneumatically transferred to a holding silo before bulk dispatch by road tanker. Process Condensates are all recovered and either reusable as water in the plant or recycled to the mine as possible.

One of the additional key features is the modular design of the Plant; effectively built as skids which allowed the bulk of the installation to be executed off site as well as facilitating moving of the Plant to other future locations if required.

The Distillation Unit was designed for a local South African steel mill to treat the preheated enriched scrubbing liquor from existing H₂S and NH₃ Scrubbers by stripping with low pressure steam. The Enriched Ammonia Liquor is first stripped of H₂S in the Deacidifier column producing Lean Ammonia Liquor, a portion of which is recycled back to the existing H₂S Scrubber, the balance pumped to the new (second stage) Ammonia Distillation Column.

In the Ammonia Column the ‘Free’ ammonia compounds are first stripped in the upper section to generate Stripped Ammonia Water, a portion of which is recycled to the NH₃ Scrubbers. The balance of the Stripped Water overflows into the bottom section of the Ammonia Still where the ‘Fixed’ ammonia compounds are released using primarily caustic soda and then stripped using steam to produce clean waste water which is discharged from the plant.

Low pressure exhaust steam is used for the stripping process and is fed to the ammonia column and then the deacidifier. The vapour exiting the plant contains the H₂S, NH₃ and HCN vapour with some steam which is discharged for further treatment by the customer.

The CO₂ Capture and Utilities Infrastructure Plant was supplied to a South African chemicals producer to provide additional utilities infrastructure (including a water-tube boiler, cooling tower, process water and steam condensate storage) and to recover CO₂ gas from the new boiler flue gas for use in their existing chemical process. Some of the utilities are consumed within the CO₂ capture and utilities plant, with the balance being exported to the existing facility.

The upgrade project included additional storage capacity for steam condensate and process water, a new cooling tower capable of cooling 1500 m³/h cooling water with a total heat load of 20MW and a new gas-fired water-tube boiler with a maximum capacity rating of 37 t/h at 21 bar (g).

A novel amine-based CO₂ capture process from Shell Cansolv was utilised to capture the CO₂ from the boiler flue gas. This comprises post-combustion CO₂ capture technology by chemical absorption using a modified amine solvent as the absorbent. The outstanding feature of this technology is the high steam economy per ton of CO₂ produced.

The entire project was managed by JordProxa Africa from technology selection and customisation through process design, detailed design, construction and commissioning. This complex project was completed within a 22 month period on a complete LSTK contractual basis without a single reportable lost time injury throughout. The plant operates very well, meeting and or exceeding all capacity requirements and produces an exceptionally pure CO₂ product.

The crystalliser was supplied to a Brazilian Vanadium producer to recover sodium sulphate and a concentrated mother liquor stream (containing ammonium sulphate) for reuse in the vanadium extraction process.

The sodium sulphate MVR crystalliser is designed to process barren liquors derived after precipitation of ammonium metavanadate (AMV). The process is complicated by impurities associated with the vanadium process, in particular ammonium sulphate and sodium vanadate. In addition, the liquor contains chloride ions at a sufficient concentration to build up in the circuit, increasing corrosion rates at low pH. This necessitated the construction of equipment in corrosion resistant materials such as super duplex, high alloy materials and titanium. Crystals are formed through evaporation which are then separated for reuse in the vanadium extraction process. The plant consists of a single effect mechanical vapour recompression (MVR), forced circulation crystalliser. A two stage MVR Fan set is used to recompress the vapour which presents a durable, easily maintainable compression device for this remote location. Two parallel solids handling trains, each incorporating a hydrocyclone, screen-scroll centrifuge and a screw conveyor ensure high overall plant availability.

JordProxa Africa designed and supplied the client with two steam heated, falling film evaporators, operating under high vacuum to concentrate 76% ammonium nitrate up to 96% . These units more than double the existing liquid ammonium nitrate evaporation capacity at the customer’s site, and proves to be a more cost effective solution for this duty than the existing air swept unit. The evaporator set generates a stream of process condensate equivalent to the required evaporation rate, i.e. approximately 3t/h. There is no contaminated air plume (as associated with air swept units) and the only emission to atmosphere is a small steam discharge from the vacuum ejector.

JordProxa Africa designed and supplied equipment for a Falling Film (FF) evaporator with a mechanical vapour recompression system (MVR) which was installed to pre-concentrate the dilute sodium nitrate feed to a 25wt% solution. The bulk of the required evaporation takes place in this new FF evaporator, allowing the existing crystalliser to undertake the remaining evaporation and crystallise the solution. Slurry from the crystalliser is then processed through a new centrifuge, flash dryer, coating system and off-gas scrubber. An automated bagging unit packages the crystals into 25kg bags, which are manually palletised and stored.

Another existing plant, a triple effect evaporator / crystalliser, was modified and re-used to concentrate the dilute potassium nitrate feed to a 24wt% solution. The concentrated solution is purged to a new storage tank, loaded into tankers, and transported to a bottling plant at a separate location.

JordProxa Africa was also responsible for the design and supply of equipment associated with the modifications to the two existing crystallisers.

The aim of this project was to provide the client with a sustainable effluent treatment program, producing saleable sodium chloride and clean process condensate. The presence of high concentrations of calcium chloride within the lime treatment product stream precludes removal by crystallisation, and thus the calcium is removed from the evaporator feed stream in a two stage precipitation process. The solids from the circuit are recovered and washed on separate filter presses and disposed of as a soil additive. A triple effect forced circulation, sodium chloride crystalliser allows for treatment of 140Ml/annum clarified brine. The dewatered salt is bagged for subsequent out-loading by truck and transport off-site. In addition, a small, forced circulation mixed salt crystalliser is provided to process a contaminated purge from the salt crystalliser. This enables the generation of clean salt for sale.

The presence of corrosive organic acids complicated the plant design, necessitating the extensive use of rubber-lined steels, fibre reinforced plastics, titanium and Teflon lined piping. The project was undertaken on an equipment supply basis with the customer employing their own EPCM contractor for overall project management.

One of JordProxa Africa's main strengths is the design and construction of crystallisers in a variety of different applications. In this instance, the client's feed was a dilute nickel sulphate stream from a leach filtration plant. The feed also contained significant levels of free acid.

The mandate was to minimize overall energy costs and the result was a falling film pre-concentrator followed by a Draft Tube Baffle (DTB) crystalliser operating under high vacuum in order to crystallise the desired hydrated crystal. The entire plant was constructed out of SAF2205 to resist the effect of chlorides at the low pH and high temperatures experienced on the plant. The crystals from the crystalliser are dried in a circular fluid bed dryer and the final product is bagged in 1 ton bags.

Special design features include a single body four stage falling film evaporator incorporating a single high lift MVR fan for high energy efficiency. Use of a DTB crystalliser enables the growth of larger crystals, improving dewatering, drying and final product quality.

An upstream pre-treatment plant has been added since to produce battery grade nickel sulphate hexahydrate crystals.