Transcription
SilverRefining Plant
BenefitsThe Metso Outotec Silver Refining Plant solution covers the full range of process steps andmaterial-handling streams, from silver Doré anodes to silver granules and bars. It offers anunbeatable combination of innovative process technology, efficient handling, high flexibility,and safety. We also offer a full suite of support services to help you maximize plant uptime,including spares delivery and installation, and remote assessment of equipment status.2 Short process time and lowinventory High total recovery ( 99.8%) 99.99% Ag-purity in cathodesilver Safe working environment withno toxic gas emissions Highly automated processwith low maintenance andmanpower requirements High throughput from Dorémetal to fine silver
Principal process operations and equipmentSilver Doré anodecasting machineCleaning andwashing equipmentSilver anode slimeto gold refineryAnode scrapto reactorDryerCirculationtankSieve hefilterCementationtankGranulationequipmentSilver barcasting wheelCement silverto smeltingSolution toeffluent treatmentSilver granulesSilver bars3
Easy operation and high efficiencyThe Metso Outotec Silver Refining Plant is the result ofmore than 20 years’ experience in developing robustand cost-effective solutions for precious metals refining.The process has been successfully applied worldwide ininstallations with annual plant capacities ranging from 30 to2000 tons. Our electrorefining process produces fine silver,free from unwanted impurities, and separates valuableimpurities such as gold and platinum-group metals (PGM)from silver for recovery.The sophisticated control system monitors and controls theprocess, making it both easy to operate and highly efficient.Silver Doré anode castingWe offer various solutions for silver Doré anode casting.Our portfolio includes six different designs of both castingwheels and machines for the casting of anodes of variableweights and shapes.Metso Outotec silver electrolysis tankhouseThe heart of the Metso Outotec Silver Refining Plantprocess is the silver electrolysis tankhouse, which consistsof electrorefining cells, circulation tanks and pumps, sievetanks, a cooling system, and a pH control and adjustmentsystem. A sophisticated control system monitors andcontrols the process, making it both easy to operate andhighly efficient. With Metso Outotec HCD (High CurrentDensity) silver electrorefining cells, current densitiesexceeding1000 A/m2 are possible, dependingon the compositionof the silver Doré anodesbeing processed.4The electrorefining process is continuous except when newsilver Doré anodes are loaded in the cells and silver anodeslime and anode scrap is discharged from the cells at the endof the electrolysis cycle.The anodes continuously dissolve, depositing refined silver onthe cathodes. The cell is equipped with an automatic scrapersystem that removes the deposits – the silver crystals scrapedoff the cathodes are collected at the bottom of the cells. Atthe end of the electrolysis cycle, a slurry containing crystals ofcathode silver and electrolyte is discharged into a sieve tank.The quality of the silver crystals produced in the electrolyticrefining process is ensured by electrolyte circulation.All this helps increase the efficiency of the process, decreasemanual work, and increase the amount of silver recovered. Themodular design makes it easy to scale the solution for yourdesired capacity.Silver anode slime containing valuable impurities such as goldand platinum-group metals (PGMs) is also formed during theelectrolysis process. The slime is collected inside anode bagssurrounding silver Doré anodes and can be further processedusing the Metso Outotec Gold Refining process for recovery ofgold and PGMs.The non-dissolved anodes remaining after electrolysis arerecycled for smelting and casting of new silver Doré anodes.Spent electrolyte withdrawn from circulation is replaced withfresh silver nitrate electrolyte in order to keep the silver contentat a constant level.Silver DoréanodeCathodeSilver crystalsScraperCathodeAnode bagCellSilver anodeslimeHCD Silver Electrorefining Cell
Metso Outotec silver electrolyte preparation systemSome of the silver crystals produced in the silverelectrorefining cell are processed in the Metso Outotec silverelectrolyte preparation system, where they are dissolvedto produce pure silver nitrate solution. The process andequipment design avoids the formation of toxic NOx gases,which improves the safety of the working environment. Thesystem is also available as standalone equipment with itsown control system.Drying of silver crystalsThe final product can be either silver bars or silver granules.In both cases the silver crystals are dried using the fullyautomated Metso Outotec Silver Dryer, which consists ofa fan, a heater, and a sieve tank for the silver crystals. Thedried silver crystals are then melted using an inductionfurnace.Casting and bar processingCasting of silver bars is performed using an Metso OutotecSilver Bar Casting Wheel for 1000 troy ounce (approximately31 kg) ingots. The bars are then cooled in a water bath.Further operations, such as polishing, weighing, marking,and stacking can be performed by the Metso Outotec SilverPWMS Robot. The equipment produces silver bars that meetthe requirements of the London Bullion Market Association’sGood Delivery standards.Metso Outotec Silver Electrorefining CellsGranulation and packingMetso Outotec Silver Granulation Equipment consists of aninduction furnace, granulation equipment and a receivingtank. Granules are dried in the Metso Outotec Silver Dryerand packed using a material-handling system that producesready-to-ship bags that are sealed and marked.Metso Outotec Silver Doré Anode Casting MachineMetso Outotec Silver Bar Casting Wheel5
From single equipment to full turnkey plant deliveryMetso Outotec offers proven technologiesand equipment packages for the whole silverproduction chain, from mine to refined metal,and from single equipment to full turnkeyplant delivery. Through continuous researchand development we ensure that you arealways able to take advantage of the latesttechnologies for environmentally sustainableand economically viable silver production.Metso Outotec offers proventechnologies and equipmentpackages for the whole silverproduction chain6A lifetime of supportMetso Outotec is committed to supporting your operationsthroughout the plant life cycle, helping you achieve andmaintain peak performance levels and guaranteeing the bestlong-term return on your investment. Our global network ofservice centres covers more than 25 countries and provideslifecycle services covering everything from spare parts,maintenance, and technical services to modernizations,operations and maintenance agreements, training, andconsultancy.1. Design and installationA good basis for future cooperation starts at the beginning.We design the most realistic and suitable process solutionfor you through active participation in feasibility studiesand engineering. Then, efficient installation proceduresand professional commissioning during the delivery phaseensure that planned time-to-cash remains on schedule.Comprehensive training before start-up establishes efficientoperations right from the start.2. Operation and maintenanceDuring the operation phase, you want to achieve as highproduction rates as possible. We are able to support this goalin several ways – from simple inspections and maintenancesupport to continuous site presence and operationalresponsibility for the entire plant. The various productionchallenges you face can be systematically targeted throughprocess and metallurgical expertise, as well as maintenanceexcellence.3. ModernizationOperating conditions tend to change over time, so theproduction process and equipment may need to be finetuned or modernized to meet new requirements. We maintaina wide portfolio of modernization solutions for preciousmetals technology to ensure you continuously achieve thehighest production and quality levels.
7
Metso Outotec Corporation, PO Box 1220, FI-00101 Helsinki, Finlandtel. 358 20 484 100, fax 358 20 484 101mogroup.comCopyright 2021 Metso Outotec. All trademarks and registered trademarks are the property of their respective owners.Metso Outotec is a frontrunner in sustainable technologies, end-to-end solutions and servicesfor the aggregates, minerals processing and metals refining industries globally. By improving ourcustomers’ energy and water efficiency, increasing their productivity, and reducing environmentalrisks with our product and process expertise, we are the partner for positive change.
Silver Bar Casting Wheel for 1000 troy ounce (approximately 31 kg) ingots. The bars are then cooled in a water bath. Further operations, such as polishing, weighing, marking, and stacking can be performed by the Metso Outotec Silver PWMS Robot. The equipment produces silver bars that meet the requi
