EKATO
Minerals and Metals Processing
Maximum efficiency and durability under the most challenging conditions
Importance of hydrometallurgical processes in minerals and metals processing
Hydrometallurgical processes are playing an increasingly central role in metal extraction and processing. Many of the ores mined today have a low metal content, which makes extraction difficult and cost intensive.
Hydrometallurgical processes such as atmospheric leaching and autoclave leaching solve this problem. These methods are more effective and less expensive than pyrometallurgical processes, for example, which require high energy input and strict environmental controls. Efficient mixing technology plays a decisive role in these hydrometallurgical processes.
Resource-efficient metals extraction requires innovative mixing technology
EKATO is one of the leading experts for efficient agitator technology in the field of minerals processing. With pioneering and innovative mixing technology solutions in hydrometallurgical ore extraction processes, EKATO has established itself as a reliable partner in the industry.
Our expertise in minerals and metals extraction covers a wide range of metals extraction processes such as:
Gold extraction
Carbon in leach (CIL) or carbon in pulp (CIP)
In the carbon-in-leach (CIL) process, the crushed ore is mixed with a cyanide solution in stirred tanks. Activated carbon is then added to the mixture, which adsorbs the gold and copper from the cyanide solution. The slurry containing the dissolved metals and the activated carbon is then passed through a series of tanks where the activated carbon is separated and the metals are recovered.
In the carbon-in-pulp (CIP) process, similar to CIL, the crushed ore is mixed with a cyanide solution. In the CIP process, however, the mixture is not stirred in separate tanks but directly in the pulp with activated carbon. The carbon adsorbs the gold and copper while the slurry passes through the tanks. The loaded activated carbon is then separated from the slurry and fed into the elution circuit for metal recovery.
Pressure oxidation (POX)
The pressure oxidation process is primarily used for ores with a high sulphide content, where conventional cyanide extraction processes are less effective. In such cases, pressure oxidation is used to break up these resistant minerals and release the desired metals, usually gold or base metals, for subsequent extraction. This takes place in a stirred autoclave with several chambers under high temperatures and pressures and with the addition of oxygen in an acidic environment.
Bioleaching, bio-oxidation (BIOX)
Bioleaching is an alternative process to pressure oxidation. In bioleaching, bacteria are used to dissolve metals from sulphide minerals and convert them into soluble forms that can be easily recovered. This process is particularly effective for low-grade ores and complex sulphide minerals.
Biooxidation, on the other hand, is a similar process that is specifically targeted at refractory gold ores. Microorganisms are used to oxidize gold-bearing sulphide minerals, making the gold accessible for extraction by conventional methods such as cyanidation. Mixing is critical in these processes for several reasons.
Silver extraction
Cyanide leaching
The hydrometallurgical process for silver extraction in which agitators and mixers are used is the leaching process (in particular cyanide leaching). In this process, silver is extracted from its ore through a chemical reaction in an aqueous solution containing cyanide ions. Agitators and mixers ensure uniform mixing of the ore particles and the leach solution to maximize the contact time and therefore the efficiency of silver dissolution.
Nickel and cobalt extraction
High-pressure acid leaching (HPAL)
The HPAL process (High Pressure Acid Leach) for the extraction of copper and cobalt uses high-pressure agitated reactors in which the ore is digested at high temperatures and pressures in a sulphuric acid solution. Agitators and mixers ensure uniform mixing of the ore-acid suspension in order to optimize the reaction kinetics and maximize contact between the particles and the acid. The acid treatment releases copper and cobalt from the minerals and dissolves them. These metal solutions are then separated and purified by further processes, such as solution extraction and electrolysis, and further processed into pure copper and cobalt. The agitators and mixers play a crucial role in maximizing the efficiency of the digestion process and the recovery of the metals.
Copper extraction
Acid leaching (sulphuric acid)
In the acid leaching of copper, crushed copper ore is mixed with sulphuric acid in an agitated reactor, with agitators and mixers ensuring uniform mixing and maximum reaction efficiency. The copper dissolves in the acid as copper sulphate, while the insoluble material is separated. The copper sulphate solution is then further processed to obtain pure copper.
Bio leaching
Copper bioleaching uses special bacteria to dissolve copper from ore in an agitated reactor. The ore is mixed with a bacterial solution and the agitators and mixers ensure uniform mixing, maximizing contact between the bacteria and the ore. The bacteria oxidize the suphide minerals in the ore, releasing the copper as soluble copper sulphate. The resulting copper sulphate solution is then separated and further processed to recover pure copper. The agitators and mixers are crucial to ensure the efficiency of the biological process and to promote the oxygen input necessary for bacterial activity.
Aluminum extraction
Bayer-process
The crushed bauxite is mixed with caustic soda in a stirred reactor using the Bayer process. The agitators and mixers ensure uniform mixing, which efficiently dissolves the aluminum oxide from the bauxite, while the insoluble components remain behind as red mud. The resulting sodium aluminate solution is separated from the red mud and converted into pure aluminium hydroxide through cooling and crystallization. The aluminum hydroxide is then heated by calcination to aluminum oxide (alumina), which is finally reduced to aluminum in a smelting process. The agitators and mixers are crucial to increase the reaction speed and ensure a high yield of aluminum oxide.
Uranium extraction
Acid leaching (sulphuric acid)
The hydrometallurgical process for uranium extraction in which agitators and mixers are used is the acid leaching process. In this process, uranium ore is treated with sulphuric acid in large tanks to dissolve the uranium. Agitators and mixers ensure uniform mixing of the acid and the ore, which increases the efficiency of uranium dissolution and ensures a uniform reaction.
Zinc extraction
Acid leaching (sulphuric acid)
In the hydrometallurgical leaching process for zinc extraction, crushed zinc ore, often zinc sulphide, is mixed with diluted sulphuric acid in an agitated reactor. The agitators and mixers ensure thorough mixing of the ore-acid suspension to ensure an optimal reaction in which zinc goes into solution as zinc sulphate. After leaching, the zinc sulphate solution is separated from the solids. The zinc sulphate solution is then purified and reduced to pure zinc by electrolysis. The agitators and mixers are crucial to maximize the effectiveness of the leaching and improve the yield of the process.
What sets us apart at EKATO is our continuous commitment to innovation and excellence in agitator and mixing technology. Through our modern research and development (link to process development R&D), we are constantly setting new standards, whether in the optimization of mixing processes, the extension of product life or the development of flow-optimized agitators. Our material technology guarantees wear-resistant solutions that can withstand the most demanding requirements.
Our customers trust that EKATO not only supplies high-quality products, but also makes a sustainable contribution to the efficiency of their processes through significant energy savings. These energy savings and the long-lasting, low-maintenance agitators and mixers allow our customers to make considerable cost savings in the operation of their plants. With a decades-long track record and a global network, we are proud to be shaping the future of agitator technology and meeting the challenges of modern hydrometallurgical ore extraction with innovative solutions.
Efficient mixing technology and reactor concepts for your metal extraction process
In hydrometallurgy, three system types or mixing vessel concepts are of particular importance from a mixing technology perspective: autoclaves, atmospheric vessels and leaching vessels. EKATO is the world market leader in the field of mixing technology for autoclaves. Based on decades of experience, we focus on customized mixing solutions.
We understand our customers’ processes and offer them an optimal agitator concept, even beyond the agitators and mixers.
Our services range from
- Laboratory tests with the original product
- CFD analyses for an optimized flow rate
- Scale-up to industrial scale
- Finite element analysis and calculation of the dynamic loads on both the agitator and the tank internals
- Definition and conceptual design of the optimum feed points and tank internals
- Customer-specific design and manufacture of the agitators and mixers
- Worldwide service on site
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More InformationCompared to previous solutions available on the market, our agitators and mixers are characterized by the following advantages:
- Higher yields and improved hydrometallurgical results due to improved mass transfer and higher circulation rates to suspend solids.
- Significant cost savings due to higher gas yield.
- Reduced operating costs due to stable operating behavior even at very high gassing rates.
- Longer operating life of the agitators and mixers due to modern materials and flow-optimized geometries.
Mixing solutions for autoclaves and tanks in hydrometallurgy
Autoclaves
Autoclaves are used in hydrometallurgy when leaching with conventional atmospheric methods is uneconomical. Typical autoclave applications are:
• Pressure oxidation autoclave (POX) for gold extraction
• High pressure acid leach autoclave (HPAL) for nickel extraction
Autoclaves are usually horizontal vessels divided into 3 to 9 chambers or a cascade of vessels, which are operated at high temperature and high pressure. The extreme operating conditions put a strain on the equipment in terms of abrasion, corrosion, high dynamic loads and changing and fluctuating pressure conditions. This requires top quality products individually designed for the process conditions to ensure maximum availability and service life of the agitators and mixers and to keep operating and maintenance costs as low as possible.
What are the advantages of our agitators and mixers for pressure autoclaves?
EKATO offers comprehensive solutions for pressure autoclaves in the minerals processing sector that have been specially developed for the extreme conditions in this area of application. By combining agitators, mechanical seals and supply systems from a single source, our customers benefit from a longer service life, reduced maintenance intervals and lower maintenance and operating costs.
Our agitator devices enable seals to be replaced quickly and easily – within a few hours and without the need for time-consuming disassembly of the drive. This minimizes downtimes and increases the efficiency of the process.
The flow-optimized agitator elements, some of which are also available with different coatings or made from innovative ceramics, are extremely resistant to abrasion and corrosion. This leads to a significant extension of product life cycles, in some cases many times over, and therefore to significantly lower operating costs.
We also ensure the optimum design and positioning of the product, acid and gas supply lines as well as the baffles. This maximizes mass transfer, resulting in faster process times and increased overall system efficiency.
Atmospherically gassed vessels
Atmospheric gassed mixing tank cascades in continuous operation fulfill a key function in many hydrometallurgical leaching processes, e.g:
• Biological leaching with atmospheric oxygen
• Autothermal direct leaching
• Pre-oxidation of gold-bearing ores
• Cyanide detoxification
• Immobilization of arsenic
• Iron precipitation
• Leaching with chlorine gas, e.g. for further processing of nickel matte
• Extraction of scandium and rare earth metals with SO2 gas
• Production of high-purity lithium carbonate using CO2 gas
In addition to cost degression through the construction of ever larger agitated units and process improvements, overall cost optimization is a key objective.
What advantages do our agitators and mixers offer for atmospherically gassed tanks?
We offer customized agitator solutions for atmospherically gassed mining tanks that impress with their efficiency and cost savings. Our innovative agitator and mixer gassing concepts enable considerable savings in terms of compressor performance, among other things, which in many cases can lead to savings on entire compressors. This not only considerably reduces the investment costs of the overall system, but also significantly lowers ongoing operating and energy costs.
From our wide range of gassing agitators, we can always offer the optimum and most efficient solution, specially adapted to the required gas quantities, the suspension challenges and at economical prices.
Our VISCOPROP and ISOJET-B hydrofoil impellers are ideal for low to medium gas rates. For high gas rates, the particularly efficient EKATO COMBIJET and EKATO COMBIJET PLUS solutions are used, which have a very low power loss even with high gas volumes and enable a cost- and energy-efficient agitator design.
Our optimized aeration concepts prevent flooding of the agitators and clogging of the aeration holes, which is a common problem with conventional aeration rings. The improved dispersion significantly increases the mass transfer, which leads to more efficient processes and shorter production times.
Overall, these advantages contribute to a significant reduction in the operating and maintenance costs of the system.
Leaching tanks & atmospheric tanks
As rich ore deposits are diminishing and demand for raw materials continues to grow, the processing of low-grade ores is becoming increasingly important. An unbroken development here is the expansion of production units in order to be able to process the increasing throughputs more economically. The large agitators required for this must be very robust and reliable in order to ensure plant availability even over several years in rough everyday operation. The mixing tasks range from demanding suspension tasks with high solids loads to the homogenization of pasty suspensions with non-Newtonian flow properties. Typical applications are:
• Leaching tanks, e.g. gold-bearing ores (CIL, CIP) and non-ferrous metal ores (zinc)
• Homogenization of non-Newtonian suspensions with high solids content, e.g. in storage tanks for autoclaves as well as storage and intermediate tanks for slurry pipelines
• Mixing and conditioning tanks, e.g. CCD intermediate tanks, mashing of filter cakes
• Storage and buffer tanks to compensate for production fluctuations
What are the advantages of our agitators and mixers for atmospheric mining tanks?
Our agitators and mixers are specially designed for the extreme requirements of mining. Our mechanically robust agitators and mixers are precisely designed for the various operating conditions required. Whether operating in various critical filling levels with significantly increased forces on the agitator, high solids concentrations and different particle sizes, we always design our agitators with sufficient safety.
Our experts offer comprehensive advice and conceptual design to optimize the operating mode with regard to fluctuating dynamic forces, energy efficiency and challenging suspension tasks. This guarantees trouble-free and efficient operation of your system.
The flow-optimized impellers ensure efficient mixing and thus ensure a process flow and prevent deposits in the tank.
Our impellers are available with various coatings (such as rubber coatings, wear-resistant silicon carbide materials…), are extremely resistant to wear and corrosion, which extends product service life and significantly reduces maintenance intervals. This means you benefit from lower operating costs and higher system availability. If our customers have extreme abrasion problems, our industrial ceramic impellers are the proven solution!