ote outotec hydrometallurgical technologies for zi

Outotec hydrometallurgical technologies for zinc

Environmentally sustainable zinc solutions

Outotec's expertise and experience provide the path to optimized solutions and complete plants for the production of high-quality zinc, based on a wide range of zinc raw materials. Outotec offers innovative and proven roasting, leaching, precipitation, solution purification, solvent extraction, electrowinning and casting technologies as well as sulfuric acid plants.

002 Outotec hydrometallurgical technologies for zinc

Outotec operates globally through a broad network of sales and service centers. We strive to build a long-term relationship with our customers, ensuring that they receive the very best solutions for their operating environment. Our expertise covers the whole chain of zinc production, from concentrator to zinc casting equipment. Outotec's early involvement in projects ensures the most profitable and competent solutions.

We provide world-leading technologies, technology selection expertise based on laboratory test programs, feasibility studies, basic and detailed engineering, technology specific equipment supply, training, erection supervision and start-up assistance, as well as follow-up and technical support services. Such involvement, from a single partner, offers you the possibility to enhance your production processes and minimize operating costs throughout the lifetime of the plant.

A committed partner from the start

Outotec offers: n Innovative and proven technologies n Laboratory test programs and

pilot test campaigns n Feasibility studies n Basic and detailed engineering n Proprietary and key equipment supply n Commissioning and start-up services n Process automation n Spare parts and maintenance services n Plant audits, retrofits and

machine upgrades

Outotec hydrometallurgical technologies for zinc 003

Oxidic andsilicate zinc ore andsecondaryraw materials

Sulfidic zinc concentrate

Zinc ingot

Calcineleaching

Iron removal/Neutralisation

Solution purification

Concentratedirect

leaching

Casting

-Electrowinning

Solvent Extraction

Oxideleaching

Roasting

Caring for the environment

Outotec zinc technologies are designed to minimize environmental impact. We strive to make effective use of raw materials, minimize the production of stable or re-usable residues and reduce water and energy consumption.

Outotec zinc technologies comply with the environmental legislation and requirements. Outotec's early project involvement ensures smooth environmental performance of the zinc production chain. Outotec designs the most favorable and environmentally compatible solution according to your operating conditions.

Outotec zinc technologies: RoastingSulfuric acid plantLeaching:

n Atmospheric direct leaching of zinc concentrate

n Zinc calcine leaching n Zinc silicate leaching n Leaching of secondary raw

materials e.g. EAF dustPrecipitation processes:

n Iron precipitation n Neutralization

Solution purification: n Copper removal n Chloride removal n Cobalt and nickel removal –

Arsenic or antimony process n Cadmium removal n Gypsum removal

Zinc solvent extractionElectrowinningZinc castingEffluent treatment Residue treatmentReactors and equipmentProcess automation

Tailor-made solutions through inhouse research and developmentComprehensive laboratory testing and piloting facilities

At the start of each project, Outotec's in-house research centers play an important role in actively developing and acquiring technologies according to customer needs and requirements. Our research centers have a unique set of research facilities and pilot plants, from bench-scale to industrial scale, well-equipped laboratories and an extensive network of research subcontractors. At our pilot plants, we test our customers' raw materials and feedstock, and tailor our processes accordingly. For example, in order to improve the atmospheric direct leaching process, we perform a mineralogy study of the feed material, based on which we conduct a batch-leaching test followed by a continuous pilot test to obtain process design data. Through this type of commitment, we are able to provide you with an optimized process with high guaranteed process performance figures.


Continuous bench scale pilot, zinc leaching process at Outotec Research Center in Finland

Innovative leaching and precipitation methodsAtmospheric direct leaching of zinc concentrate

Outotec has developed a pioneering leaching method for zinc concentrate. The highly cost-effective and environmentally friendly process has been tested and proven on an industrial scale.

The zinc concentrate is leached in sulfuric acid, either co- or counter-currently. Direct Leaching Reactors provide the essential dispersion of oxygen and slurry required for the related reactions. Online process control with Outotec® OTI Titrators and Courier® analyzer guarantees reliable and smooth operation.


Benefits of atmospheric direct leaching: n Simple reactor construction n High metal recovery n Low operating costs n Low maintenance need n Easy to control n Low energy requirement n Low investment cost

n Compact layout n No explosion risk n No molten sulfur n High availability n Flexibility with respect to various feed material n Concentrate with low zinc content may be used n Proven technology on an industrial scale

The process is extremely flexible with respect to different raw materials and variations of feed materials. By using Outotec's atmospheric direct leaching, zinc recovery exceeds the industry norm. Atmospheric direct leaching can easily be constructed as stand-alone or combined with calcine leaching.

The iron can be removed as jarosite or goethite. As a result of the precise control of iron oxidation and the acidity of the process solution, precipitation is carried out either during or after the leaching process, depending on customer's needs.

Zinc calcine leaching

Zinc calcine produced in roasting contains zinc oxide and zinc ferrite. In order to obtain the maximum amount of high-quality zinc, the two must be leached in different conditions.

Firstly, zinc oxides are leached in neutral leaching stages, during which ferrites do not dissolve. This process involves OKTOP® reactors and Outotec® High Rate Thickeners arranged in a cascade, with the acidity kept low.

Secondly, the underflow flows onto the Outotec conversion process, where the zinc ferrites are leached simultaneously with the precipitation of jarosite. This stage has proven low investment costs and a confirmed low environmental impact.

Outotec provides an alternative solution to neutral leaching residue with high lead and silver content. The residue is leached in two counter-current Outotec hot acid leaching steps, in order to leach the incoming zinc ferrite to obtain an overall high zinc recovery and simultaneously to produce a leach residue with highest possible lead and silver content. The overflow is fed into the iron precipitation stage.

Zinc silicate leaching

Outotec has developed a leaching process also for zinc silicate and zinc carbonate ores. Special attention in the design is paid to the solubility and kinetics of silicates, which offers high zinc recovery and stable process operation. In addition, Outotec tailor-made process solution enables to optimise acid consumption in the leaching and to make processing of such a raw material economically viable.

Leaching of secondary raw materials

Processing of secondary zinc raw materials and recycling of zinc are increasingly important. Outotec has designed a process to treat secondary zinc raw materials like electric arc furnace (EAF) dusts as well as Waelz oxides to produce Special High Grade (SHG) zinc. These raw materials with high chloride and fluoride content can be treated by a combination of Outotec leaching and solvent extraction processes.

The halide concentration in the process circuit can be efficiently controlled by washing of the oxide before the leaching step. Outotec offers various methods to control the impurity levels in the solution to guarantee trouble-free operation and to meet even the highest environmental regulations for the process outlet streams.

Zinc can be recovered with exceptionally high recovery and low investment and operation costs with Outotec know-how in the leaching and solvent extraction processes combined with our process equipment and optimised equipment material selection.


Benefits of Outotec oxide and silicate leaching: n Low investment cost n Low environmental impact n Simple process n Flexible and adaptable n Improved process performance

through optimized reactor design


Iron removal

Outotec offers jarosite and goethite processes for iron removal. Outotec processes have been proven to produce iron precipitate with a low zinc and high iron content. During iron precipitation, it is essential that the operating conditions can be controlled, in order to produce iron as the desired compound. This is mainly accomplished through optimizing the iron oxidation and precipitation rate and Outotec reactors. Furthermore, the circulation of oxygen from the gas phase back into the solution is performed in order to obtain the highest oxygen utilization efficiency.

Our expertise in iron precipitation offers an efficient and reliable solution to zinc producers for environmentally acceptable iron residue storage or further use.

Neutralization

Outotec provides an expert solution for removing metals from dilute process solutions. Neutralization is performed through the addition of lime milk;

the metals in the solution are precipitated as hydroxides and lime as crystalline gypsum. The combination of three factors, pH control, powerful OKTOP Reactor Series 4000 agitators and seed circulation, makes Outotec's neutralization plant superior. All of these factors reduce the adhesion of particles to the neutralization reactor and piping in a controlled manner. Furthermore, optimal particle size distribution, a high settling rate, and the good filtering properties of disposed solids are obtained cost-effectively through a high degree of process utilization.

Advanced zinc solution purification and solvent extraction

Copper removal

The first stage of solution purification is copper removal. Copper is precipitated from the zinc solution in a continuous and proficient way. It is essential to remove copper, as it will otherwise precipitate with zinc onto the cathode and, as a result, reduce current efficiency in electrolysis. Copper is cemented using zinc dust and copper, and cuprous oxide is produced, reducing zinc dust consumption and thus operating costs. The copper cake can be utilized in copper smelting processes.

Chloride removal

If necessary, chloride removal can be implemented at the copper removal stage. Outotec has devised an effective chloride removal method, improving the quality of zinc by keeping the chloride content under permissible levels. In order to avoid corrosion problems, it pays off to remove chloride from the zinc solution.

Outotec offers extensive solution purification processes. During leaching, other metallic components nobler than zinc such as copper, cobalt, nickel and cadmium are leached and must be removed before electrowinning.

Cobalt and nickel removal

Outotec offers cobalt and nickel removal, either using arsenic or a conventional antimony process. Cobalt and nickel are removed in Outotec's continuous arsenic process through the addition of arsenic trioxide and zinc dust. Cobalt and nickel removal is essential since the presence of these materials lowers the efficiency of the electrical current during electrolysis.

In addition, Outotec has built antimony-based purification processes all over the world and has a vast experience in this field. The antimony process is a three stage process consisting of copper-cadmium removal and separate cobalt-nickel removal, followed by polishing. Cobalt and nickel are precipitated using antimony trioxide and zinc dust.

The cobalt and nickel removal process by arsenic gives lower zinc dust consumption, higher quality of the product solution and ability to treat solutions with higher impurity levels.



SPIROK® maintains smooth mixing with

optimal reaction surface.

DOP® generates optimal droplet

distribution.

Cadmium removal

Cadmium is removed in Outotec's state-of-the-art fluidized bed system which gives the lowest possible zinc dust consumption and produces cadmium sponge with a high cadmium and low zinc content.

This cadmium cake can be briquetted and subsequently fed into a cadmium refining furnace. The refined metal can then be cast into wire or sticks, the refining process yielding 99.98% pure cadmium.

Gypsum removal

Gypsum must be removed from the zinc solution prior to being sent to the electrowinning department, as it will form crystals in the tankhouse cells. Gypsum removal is performed by cooling the solution with Outotec® Cooling Towers, and by separating the precipitate from the main zinc solution using Outotec High Rate Thickeners.

Continuous and efficient control of the process is essential in order to extract the maximum amount of gypsum.

Zinc solvent extraction

Solvent extraction is an alternative to zinc solution purification by metals precipitation and is especially suitable for solutions with lower zinc concentration.

Outotec offers innovative solvent extraction technology. Our expertise covers the chemistry of the related processes and how to implement it, alongside high-performance equipment, in a zinc solvent extraction plant.

Zinc solvent extraction is suitable for leach solutions such as secondary, oxidic or silicate zinc raw materials. Outotec's continuous development of mixer- settler technology has resulted in ground-breaking Outotec VSF® solvent extraction technology, which significantly decreases operating costs and improves profitability. Its scalability makes this technology suitable for plants of any size. Outotec VSF comprises the Outotec DOP® Overflow Pump, two Outotec SPIROK® Mixers, and a proprietary settler design including Outotec DDG®

Separation Fences.


Optimized solution through industrial equipment designOutotec equipment solutions optimise the metallurgical results and ensure reliable operations. Outotec’s equipment is designed to be an economical solution for the entire lifetime of your plant. Furthermore, we guarantee high level equipment performance.

Outotec proprietary equipment: n OKTOP reactors n Outotec cooling towers n Scrubbers n Thickeners n Filters n Flotation cells n Cathode stripping machines n Permanent cathodes n Bales n DOP pumps n SPIROK mixers n Settlers n DDG separation fences

Outotec reactor delivery package:Agitator:

n Bridge and design of support n Electric motor n Drive n Shaft and impeller

TankBafflesIntegrated heat exchangersReactor stands or supportLaunder between reactors

OKTOP® Reactor Family

The OKTOP Reactor Family is a result of decades of experiments, design work and operational experience . The OKTOP Reactors are an optimal solution for solid-liquid, gas-liquid, gas-liquid-solid and liquid-liquid systems for leaching, precipitation, crystallization, oxidation, reduction and solvent extraction. Process performance requirements are met by configuring reactor design elements, such as the agitator, tank design and baffles.

Outotec has installed hundreds of reactors for a wide range of hydrometallurgical applications, from leaching to precipitation. We tailor our proprietary equipment according to the customer’s process requirements. We utilize our experience and expertise from numerous implementation projects in customizing our equipment to your process conditions. A complete technology package with proprietary equipment from Outotec ensures that you get an optimized process with maximal financial return.

OKTOP reactor design begins with determining the process parameters. Outotec’s comprehensive chemical knowhow is a key factor in the project and forms a solid basis for the project. The unique design cycle includes physical modelling, leaching and precipitation tests in laboratory, fluid dynamical analysis, computational mechanical design and life cycle analysis. The Outotec reactor design enables us to provide you with the optimal and most reliable equipment solution, excellent process performance and maximum equipment lifetime. The Outotec reactor design specifies optimal corrosion resistant materials and enables economical local manufacturing.



Outotec Cooling Towers

The compact and innovative new design of Outotec Cooling Towers provides high efficiency direct solution cooling with significantly lower emissions and higher cooling air throughput. Additionally the innovative top structure enables maintenance while the cooling tower is in operation leading to higher availability. Higher efficiency leads to smaller amount of towers and higher availability to lower maintenance costs. Both capital and operational costs are decreased.

Since the related emissions are therefore lower than in a conventional cooling tower, the impact on the environment is diminished. Furthermore, the cooling effectiveness allows for a more compact tower size. Housekeeping is easy due to the structure of the tower.

Scrubbers

Outotec® Ventgas Scrubber package is an efficient solution for cleaning hydrometallurgical plant off-gases. Outotec delivers several types of gas scrubbers for different off-gases in the zinc process. Scrubber design is integrated with Outotec reactors. With tailored gas cleaning solutions we can ensure maximum environmental safety for Outotec processes.Flotation cells

The world-leading Outotec® Flotation Cells enable to separate sulfur and undissolved sulfides from the zinc concentrate leach residue. The residue

reports to a separate tailings dam or lead smelter as intermediate lead/silver products depending on process configuration.

In addition, we offer tailored flotation cells suitable for zinc concentrators. At Outotec, we provide the required testing to determine the size of flotation cell and froth recovery arrangement fitting your plant. This enables compact, economical and efficient plant design.

Solid-liquid separation

The solid-liquid separation offered by Outotec comprises both thickeners and filters. Combining these technologies gives an optimal process solution which guarantees the highest possible metal recovery, control of water balance and high-purity by-products for all of the process steps in hydrometallurgical zinc production. Outotec offers pressure filters, belt filters and polishing filters, according to the requirements of each process step and customer’s targets.

The exceptional Outotec High-Rate Thickener and Outotec® Clarifier play an important role in the zinc process, when reliable and smooth plant operation are considered. Outotec pays special attention to designing feedwells, rake profiles, drive systems and control strategies. High reliability and low capital costs are just a few of the advantages.

Efficient zinc electrowinning process with jumbo cathodesOutotec is the right partner for delivering an efficient, productive and safe electrowinning plant with optimized cathode and cell sizes, current densities, busbars, and an automatic material flow of cathodes. Outotec has a vast experience in supplying zinc electrolysis processes and equipment for greenfield plants and modernizations, based on its own process knowledge, continuous R&D and technology.

The material management system, with key equipment such as automatic cathode stripping machines, anode washing/flattening machines and cellhouse cranes, ensures safe material flow and the smooth harvesting of cathodes with minimum labor force.

Alternative methods available for cathode stripping. Optional features for improving efficiency: the handling of rejected and in-feed cathodes, online washing, weighing of single cathodes.


Advanced systems for casting zinc ingots

Outotec offers full line of automated equipment to reduce human exposure to molten metal.

Benefits: n Precise control of

metal flow and ingot weight n Tireless robotic skimming n Efficient cooling and long life of the mould n Reliable robotic stacking n High capacity linear jumbo casting

Outotec electrowinning plant::Engineering services and designProprietary equipment:

n Cathode stripping machines n Anode cleaning machines n Cellhouse cranes n Aluminum cathodes n Water-cooled busbars n Highly efficient cooling towers

Our vast experience shows that a close link between process and automation design is vitally important to ensure a smooth process operation. The important aspects of automation in hydrometallurgical processes are the ability to stabilize processes and gain an overall view of production. Safety issues with respect to operation, equipment, the environment and personnel are improved in an easy and convenient manner.

These benefits are gained with smooth equipment performance and ensuring that the consumption of additive agents and chemicals is diminished and variables such as impurity levels, process temperatures and element balances are fully controlled.

Outotec Proscon® is a process automation package for transferring our knowledge and experiences to our customers. The application includes a process control system, process instrumentation and process electrification with all of the required services. Outotec uses modern, renowned and respected hardware and software manufacturers.

Stable process operation with Outotec® Automation System

Production ramp-up

MORE

100%

50%

0%Outotec automation ensures that production ramp-up is performed faster and more effectively, enabling a stable and continuous process.

FASTER

Theoretical max.Outotec automationWorst case


Benefits of Outotec automation: n Link between process

know-how and automation n Process operated as designed n Rapid production ramp-up n Continuous and stable process n Automation system pretested

before installation at plant n Smooth equipment performance n Safety of operation,

equipment and personnel n Easy and convenient operation

Outotec Automation System:Outotec Proscon

n Process control system n Process instrumentation n Process electrification

Process analyzers n Outotec Courier n Outotec OTI Titrators n Outotec sampling systems

Material management system for electrolysisOutotec CellSense™ to improve efficiency of electrolysisOutotec TIMSReporting systems

Tankhouse Information Management System (Outotec® TIMS) is a new and modern data collection, reporting and management system to integrate Outotec's material handling machines, CellSense™ monitoring and process control systems. Significant benefits are gained in increasing the energy efficiency, product quality as well as improving maintenance and safety.


Outotec services improve your process performance

Outotec's comprehensive technology transfer package can be completed with expert services and support. Our customer service operates through a global network of local units that offers not only assistance meeting the customers' needs but also a commitment to providing advanced customer support whenever needed.

Our service experts provide punctual spare parts logistics, maintenance and training, as well as assessment and consulting services that generate a competitive advantage for you.

We can tailor services efficiently to your specific needs, when considering the necessary operational and maintenance services already from the beginning of the project. As your trusted service partner, Outotec ensures an optimized operation for the entire lifetime of your plant.

Equipment services

Obtaining all spare parts and maintenance from the same organization as process and equipment design ensures that your plant runs optimally. We make sure that you receive only the highest quality parts, consumables and upgrades, that can be seamlessly integrated into your plant.

Plant and process support services

Outotec's advanced plant and process assessment, ef-X® Efficiency Explorer, indentifies the areas for potential improvements, e.g. equipment, automation systems, metallurgical processes and complete plants.

What is more, we can make it much easier for you to fulfill current and future legislation, by ensuring that your plant and processes are running as efficiently as possible, and that maintenance is being carried out proactively.

Total service package from Outotec:Equipment services

n Spare parts and spare parts management n Equipment inspections and maintenance n Training

Process support services n Process assessment n Process control analysis

Plant services n Plant assessments n Operation and maintenance support services n Upgrades and modernizations n Shutdown maintenance services

Benefits of Outotec services: n Critical original spare parts in stock n Process and equipment know-how n Minimize downtime and

unscheduled stoppages n Maximum operating performance

[email protected] © 2012 Outotec Oyj. All rights reserved.

Finl

and,

Jun

e 20

12.

Outotec develops and provides technology solutions for the sustainable use of Earth’s natural

resources. As the global leader in minerals and metals processing technology, Outotec has developed

over decades several breakthrough technologies. The company also offers innovative solutions for

the chemical industry, industrial water treatment and the utilization of alternative energy sources.

Outotec shares are listed on the NASDAQ OMX Helsinki.

ote outotec hydrometallurgical technologies for zi

Documents

atmospheric direct leaching

material management system

outotec hydrometallurgical technologies

outotec cooling towers

low zinc content

stable process operation

spare parts

solvent extraction