Tag Archives: pressure oxidation

Petropavlovsk gears up for refractory gold push with Pioneer plant launch

Petropavlovsk has announced the “technical launch” of the flotation plant at its Pioneer operations in Russia’s Far East, becoming the second facility in the gold miner’s portfolio able to process refractory gold ore and produce flotation concentrate.

Denis Alexandrov, CEO of Petropavlovsk, said: “The successful launch of the Pioneer flotation plant represents a key strategic milestone for the company. We are pleased to have commissioned the facility slightly ahead of the mid-year target we set when I joined the company last year.

“The new plant will enable Petropavlovsk to take full advantage of Pioneer’s substantial refractory ore reserves while providing an additional source of own-mined concentrate for our state-of-the-art Pressure Oxidation (POX) Hub.”

The new Pioneer flotation plant has the capacity to process 3.6 Mt/y of refractory gold ore. Once fully operational, the plant is expected to deliver more than 100,000 t/y of refractory gold concentrate for treatment at its POX Hub, the company says.

The opening of the Pioneer flotation plant doubles the group’s capacity to process refractory gold ore which, including the existing Malomir flotation plant, now stands at 7.2 Mt/y. Pioneer is expected to become fully operational by July and to produce around 60,000 t of concentrate in 2021.

Petropavlovsk said the construction of a third line at the Malomir flotation plant remains on track, and will add an additional 1.8 Mt/y of flotation capacity from the September quarter of 2022, bringing the total combined group capacity to 9 Mt/y.

“The launch of Pioneer flotation and expansion at Malomir will reduce the reliance of the POX Hub on treating lower-margin third-party concentrates,” the company added.

MOGAS eyes high-pressure acid leach, POX market growth with Watson Valve buy

MOGAS Industries has completed the acquisition of assets of Watson Valve, a US-based turnkey manufacturer of severe service valves for industries including mining.

Watson has a global install base of over 3,400 valves, primarily in the mining industry, but also encompassing the oil & gas and chemical industries, MOGAS said.

“This strategic purchase expands MOGAS’ global mining reach on valve supply and valve repair services, as well as adjacent market opportunities especially pertaining to the autoclave market,” it said. “It also provides an opportunity for MOGAS to build and strengthen its technology-driven vision for the niche pressure leach industry – both high-pressure acid leach, as well as pressure oxidation – by including long-standing mining customers to its portfolio, especially in the North American region.

MOGAS says it is committed to supporting and servicing the additional customer base brought about by this purchase, using its extensive global network of in-house and authorised repair centres.

Matt Mogas, MOGAS President and CEO, said: “This acquisition allows MOGAS to expand its product portfolio and get a step closer to achieve our vision as the dominant severe service technology company. We would like to offer our customers more options, and will continue to leverage our years of field experience to further enhance the Watson product line.”

Polymetal to expand pressure oxidation gold treatment in Russia

The Board of Polymetal International has approved the expansion of pressure oxidation operations at its operations in Russia and authorised the immediate start of construction at its POX-2 project.

A recently released feasibility study on the project showed that the second POX line would meaningfully increase the value of Polymetal’s refractory reserve base, comprising approximately 55% of total ore reserves, processing concentrates from its Kyzyl, Nezhda, Mayskoye, and Voro mines.

The project is expected to generate significant economic benefits as all refractory concentrates will be retained for in-house processing as opposed to selling to third-party offtakers. It will result in the incremental production of approximately 30,000-35,000 oz/y of gold from the same amount of feedstock and will, on average, lower total cash costs by $ 100-150/oz per ounce for 500,000 oz of annual gold production, according to Polymetal.

POX-2, which is immediately adjacent to the current Amursk POX facility in Amursk, Russia, will also allow Polymetal to create capacity for treatment of third-party refractory concentrates, a market which has grown considerably in Russia and globally in recent years, it said.

The project’s base case post-tax net present value (10% discount) was measured at $112 million and factored in a $1,200/oz gold price, 65 RUB/$ exchange rate and a total of 4.3 Mt of concentrate containing 9.3 Moz of gold processed from Kyzyl, Nezhda, Mayskoye, and Voro over a period of 23 years.

Pre-production capital expenditures were estimated at $431 million and would be entirely funded out of company’s operating cash flows, Polymetal said.

The plant’s design throughput capacity would be 250,000-300,000 t/y of concentrate, depending on the levels of sulphur content. The maximum sulphide sulphur processing capacity, meanwhile, was 48,000 t/y.

“This would complement the 200,000 t/y of concentrate and 30,000 t/y of sulphur capacity of the existing Amursk POX facility,” Polymetal said, adding that the new facility would use a titanium-lined steel autoclave operating at 240˚С and a pressure of 43 bar.

Hatch Inc will be responsible for the basic engineering, detailed engineering, POX procurement support and the supply of custom-made equipment for high-pressure and acidic processing areas, according to Polymetal. Polymetal Engineering is responsible for other processing areas, general site layout, and infrastructure.

Vitaly Nesis, Group CEO of Polymetal, said: “POX-2 leverages our core technical capabilities and creates substantial value. It also fully de-risks our business model by eliminating dependence on concentrate offtake markets. Emerging trends in the global gold mining industry make POX-2 a crucial element of the company’s long-term strategy”.

Polymetal envisages the start of detailed engineering and construction in the June quarter, receipt of all permits in the March quarter of 2020, delivery of the autoclave on-site in the September quarter of that year and completion of civil construction works around a year later.

Completion of the main equipment installation is scheduled for the March quarter of 2022, followed by completion of external infrastructure and mechanical completion and start of commissioning activities in the September and December quarters of that year, respectively.

The end of commissioning and first production could take place in the September quarter of 2023, with full ramp-up by the end of that year.

POX-2 will share some of the external infrastructure (gas main, access road, water main) with the existing POX facility. Additional electricity supply will be provided via a new dedicated power line from the regional 110 kW grid, Polymetal said.

The project will include a new hydrometallurgical area (POX proper), carbon-in-leach and intensive cyanidation areas, an oxygen plant, an upgrade to the existing dry tailings facility, reverse osmosis water treatment facility, and several smaller infrastructural facilities (warehouses, maintenance areas, etc).

POX-2 is designed for processing double refractory concentrates, which contain micron gold particles encapsulated in sulphides (pyrites and arsenic pyrites) together with high concentrations of organic carbon. “High carbon content drives high sorption activity (preg-robbing) and dictates the use of high-temperature (240˚С) pressure oxidation compared with medium-temperature (200˚С) oxidation utilized at the existing Amursk POX facility,” Polymetal said.

“Pressure oxidation was selected as the most feasible processing technology for double refractory ores. It is able to achieve gold recoveries of 96% by utilising high temperatures, elevated pressure and oxygen to recover encapsulated gold, while conventional cyanidation methods would result in sub-optimal recovery rates of 20-40%. Completed metallurgical tests on Kyzyl and Mayskoye high-carbon concentrates confirm the recovery rate of 96%.”

Polymetal’s Amursk POX facility, in 2018, produced 308,000 oz of gold-equivalent from 170,000 t of processed concentrate for a 96.7% POX recovery.

Petropavlovsk nears first gold production at POX plant

Petropavlovsk has made significant progress on the commissioning its Pressure Oxidation (POX) Hub project at the Pokrovskiy mine in the Russian Far East, with first refractory ore concentrate processing scheduled for November 28.

During the week commencing November 5, the group’s in-house POX experts together with Outotec, MOGAS Systems & Consulting and representatives from various equipment manufacturers, successfully commenced hot commissioning of the first of four autoclaves, associated flash tanks, high pressure circuits and concentrate re-grinding and lime preparation sections of the POX facility.

The hot commissioning process involved filling autoclave 1 with an acid solution that replicates the usual operational conditions under which the autoclave is processing refractory concentrate. The autoclave vessel was heated in stages over a period of three days, before being allowed to cool down over a period of two days.

“The hot commissioning process helped to expose certain minor defects, including a leak caused by a faulty seal within an agitator. All defects have now been rectified and the autoclave is being heated in preparation for final commissioning tests with refractory ore concentrate, scheduled for November 28,” Petropavlovsk said.

The flash tanks and receivers associated with autoclave vessel 1 have also successfully passed the hot commissioning stage.

In the update today, management also confirmed both the cold and wet commissioning of all other principal equipment at the POX and filtration sections of the plant have been completed, with wet commissioning confirming the quality of the welding and piping work at the POX section of the plant.

The concentrate loading, re-grinding and lime preparation sections (formerly part of the Pokrovskiy resin-in-pulp plant) have also been commissioned, and first concentrate and limestone are currently being loaded into the plant ahead of autoclave commissioning using refractory ore concentrate.

The oxygen plant has been fully commissioned and is being prepared to commence oxygen production to supply autoclave 1 once tests on refractory concentrate begin later this week.

Petropavlovsk says the company is on track for maiden gold production from the POX plant shortly, with a plan to ramp up to sustainable commercial production throughout 2019.

The development of the POX hub is aimed at supporting estimated production of 500,000-550,000 oz/y over the next five years, up from 420,000-450,000 oz expected this year.