Visit Metso at MINExpo and learn about the three biggest ways to reduce capital expenditure (CAPEX) and operational expenditure (OPEX) through circuit design. The three ways are to “reduce the quantity of operating equipment, use the most efficient equipment available and ensure that the complete comminution circuit is designed to maximize plant efficiency. With new advances in equipment, such as the Metso MP®2500 cone crusher, the Metso HRC™3000 HPGR and the Metso VERTIMILL® VTM-4500-C, new exciting solutions are pushing the boundaries of circuit design.“The same common themes for energy-efficient circuits have been discussed in countless papers. Crush more, grind less! Don’t overgrind! And, of course, a popular topic is the energy savings offered by going to an HPGR circuit instead of primary grinding. These general concepts are all valid, but they are just pieces of the bigger puzzle; there is further room for improvement.”With diminishing ore grades and rising energy costs, ensuring that a plant has the lowest total cost of ownership is vital. One way to achieve this is to reduce the number of lines in the comminution circuit with as few moving components as possible – a strategy that has been employed in SAG mill circuits for some time. From a CAPEX perspective, the single unit equipment typically has a lower installed cost than multiple smaller units. Cost savings come from a smaller footprint, a reduction in installation costs, a reduction in ancillary equipment, and shorter commissioning time, which results in quicker realization of production targets. By having a single-line circuit, equipment availability is increased as there is less equipment that needs regular maintenance and that can break down. Moreover, larger machines tend to have similar maintenance intervals as smaller machines; but with less machines to maintain, the overall plant availability can be increased.The MP2500 cone crusher, the HRC3000 HPGR, and the VERTIMILL VTM-4500-C are the largest equipment of their kind. With these machines, single line/single equipment crushing circuits up to 95,000 t/d are now achievable. However, these machines are not just known for their sheer size. They offer significant improvements over the traditional versions available to the market. Metso’s MP cone crushers are the industry standard when it comes to large cone crushing and are known for processing more ore than any competitive unit at the same reduction ratio or product size. And now, the MP2500 offers the largest available feed opening on the market, which potentially reduces the load on the primary crusher and could allow for smaller or a lower quantity of primary crushers.Metso’s HRC3000 features the patented Arch-frame and a flanged roll design, which provides increased machine capacity, improved energy efficiency, and increased roll life compared to traditional HPGRs on the market. In closed-circuit testing, the Arch-frame and flanges were shown to increase the circuit capacity by over 20% and decrease specific energy by over 10%. The Arch-frame also provides alignment that is critical for larger HPGR sizes, such as the HRC3000.Finally, the VERTIMILL VTM-4500-C is the world’s largest gravity-induced stirred mill and the only stirred mill on the market that is practical to use in a high-capacity secondary grinding application, says Metso. This means that an HRC HPGR can directly feed a VERTIMILL grinding mill. In one operating installation, two VTM-4500-C mills are in a closed circuit with multiple stages of high-frequency screens, and are accepting a feed of 90% passing 3 mm and grinding to a specification of 85% passing 74 micron at 400 t/h. Additionally, with the VTM-7000-C model now available, operators are able to further reduce the number of lines while taking advantage of the energy efficiency and footprint benefits of the VERTIMILL.Regardless of how efficient any piece of equipment is, in order to have the most profitable operation, the total comminution circuit must be designed to maximize the overall plant efficiency while providing the required liberation for the downstream processes. Every plant has different needs, and our expertise extends beyond the supply of a single piece of equipment. Metso’s experts can help provide a total flowsheet solution that fits the unique needs of your plant.
GeoProMining LLC (GPM) successfully increased recovery from sulphide concentrates in its Ararat plant from 20% to over 95%, defying expectations and targets. The plant was commissioned in June 2014 and achieved full capacity after three months. GPM owns and operates the Zod gold mine and Ararat processing plant in Armenia to produce gold and silver bullion.In order to expand, GPM needed to treat the underlying sulphide material at the Zod mine which only resulted in around 20 to 30% gold recovery through the existing conventional CIL flowsheet.In 2010, GPM approved a refurbishment project at the Zod mine and Ararat processing plant – in increased crushing capacity to deal with the harder ore and a refurbishment and re-commissioning of the existing flotation plant. Added to this was the installation of a new Albion ProcessTM plant for the oxidation of the sulphide concentrate prior to its treatment in the existing CIL plant. The new flowsheet would be configured such that the CIL would treat flotation tailings and oxidised residue from the Albion Process.The Albion Process is an atmospheric leaching process developed and owned by Glencore Technology. It uses ultrafine grinding to reduce the activation energy needed in oxidation of the sulphides, so that it can occur under atmospheric conditions. The leaching occurs in an agitated tank that uses HyperSpargeTM supersonic gas injectors to boost oxygen capture efficiency.Glencore Technology was engaged to design, supply and commission the Albion Process and to provide installation supervision assistance.The design basis for GPM’s Albion Process was oxidation of 100,000 t/y of concentrate to give an overall production of 100,000 oz/y of gold from concentrate and flotation tailings. The design recovery of gold from the Albion residue was 92% but the plant frequently achieves over 95% recovery with an overall plant-wide design recovery of 86% but commonly achieving 88%.The refurbishment project was commissioned in June 2014, with ramp-up occurring for the remainder of 2014. The plant has achieved and exceeded nameplate production, treating in fact 120,000 t/ya concentrate with an overall production of 120,000 oz/y.Further, GPM successfully achieved an overall 88% plant-wide recovery exceeding the 86% design target due to better than design performance in the Albion Process.The grade of concentrate has been more or less stable, and increased production might normally be expected to decrease as equipment is stretched. But in GPM’s case, it has successfully kept recovery above design using the Albion Process.GPM is currently evaluating an expansion project comprising a second line of an Albion Process plant.