Talvivaara to Test Bioleach Effectiveness in Finland’s Frigid Environment
Massive quantities of polyethylene pipe, along with state-of-the-art metals processing equipment, are being installed as this heap-leach project readies for startup this year


Crews from KWH Pipe, the piping system manufacturer and supplier for the Talvivaara nickel project in Finland, are
handling the task of fusing and fitting the huge amount of plastic piping required for the heap-leaching operation.
 
The Talvivaara nickel project is a rising star in the small galaxy of mines comprising the Northern European hardrock mining industry. And, like many astronomical events, the value of developing a deposit such as the Talvivaara sulphides has taken quite a bit of time before the point was reached where it became visible and understandable.

The Talvivaara deposits represent one of Europe’s largest sulphide nickel resources known to date. The 266-million-ton ore reserve is expected to support production for a mine life of 25 years. When production starts in late 2008, the Talvivaara mine will produce approximately 33,000 mt of nickel per year along with 60,000 mt of zinc, 10,000 mt of copper and 1,200 mt of cobalt as by-products.

As described by Kyran Casteel, E&MJ’s European editor, in our 2007 Nordic mining update, the Talvivaara project is located in Sotkamo, Finland. Talvivaara Mining Co. Ltd. (TMCL) and its subsidiary Talvivaara Project Ltd. were incorporated in September 2003 for the purpose of acquiring from Outokumpu (for a price of €1) the two polymetallic deposits, Kuusilampi and Kolmisoppi, at Talvivaara and developing them as a major nickel mine.

First indications of economic metal values in the Talvivaara area were found in the early 1960s. Exploration for base metals continued during 1977–1983 by the Geological Survey of Finland. Between 1989–1992, Outokumpu focused on further geological work in the area.

Although the deposits offer an advantageous stripping ratio for open-pit mining the nickel grade is low and consequently the prospect was never developed before Outokumpu decided to exit mining. However, in parallel with the company’s exploration of the deposits, Outokumpu’s Research Center had developed an applicable, low-cost bioheapleaching technology for treating the ore. In February 2004, the new group, led by Pekka Perä, previously the project manager of mining at Arctic Platinum Partnership from 2001 to 2003 and project manager at Pyhäsalmi Mine Oy, acquired the rights to mine the Talvivaara deposits and the rights to use the related geological and bioheapleaching research data.

Following the acquisition, the group obtained development financing from Tekes, the Finnish government’s Funding Agency for Technology and Innovation. With this funding, the group continued the development of the bioheapleaching technology in cooperation with Finnish universities and in 2004 started the environmental impact assessment of the Talvivaara project, which was completed in December 2005. Meanwhile in June 2005, construction of an on-site pilot heap to test bioheapleaching started and the initial process commenced in October 2005. Pilot runs of the metals recovery process were carried out from March to September 2006.

In March 2007, the board of Talvivaara Project approved a bankable feasibility study, containing detailed estimates of all material capital and operating expenditures expected to be incurred in connection with constructing and operating the project; obtained an environmental permit and also obtained other material permits required for the commencement of mining operations. The Talvivaara deposits comprise one of the largest known sulphide nickel resources in Europe. At full production, TMCL has the potential to provide approximately 2.3% of the world’s current annual production of nickel by 2010.

As a result of the original deal with TMCL, Outokumpu gained a stake in TMCL but, while the stainless steel producer says it supports and endorses the project for strategic reasons, the holding is classified as an available-for-sale financial asset with changes in fair value recognized directly in equity. Metso has an interest in the group as a result of collaboration on process development and Norilsk Nickel gained a holding as a result of having purchased OMG’s Harjavalta nickel refinery in March 2007. Talvivaara has a 10-year off-take agreement with Norilsk Nickel for 100% of the new mine’s nickel and cobalt output.

The group has obtained an environmental permit for commencement of mining operations and other material permits required for the commencement of mining operations. In early April of this year, the company announced that it had detonated the first ore blast in the pit, signaling the start of mining. The next key milestones are the start of stacking and leaching of the ore in July and commencement of metals production during the fourth quarter of 2008.


Pannevis RB-SV filters like these from Larox will be installed in the Talvivaara plant.
 
Finland’s Largest Surface Mine
The process flow in Talvivaara will consist of four main steps: mining, crushing, bioheapleaching and metals recovery. Openpit mining is planned to be at a scale of approximately 15 million mt/y, making it the largest open-pit mine in Finland. Three-stage crushing will be followed by agglomeration with sulphuric acid in order to consolidate the fines with coarser ore particles. After agglomeration, the ore will be conveyed and stacked 8 m high on the primary heap pad for 18 months of bioheapleaching. After the primary leaching interval, leached ore will be reclaimed, conveyed and restacked onto the secondary heap pad, where it will be leached further in order to recover additional metals After secondary leaching, the barren ore will remain permanently on the secondary heaps. In metals recovery, nickel, copper, zinc and cobalt are precipitated from the pregnant leach solution and filtered to produce saleable metal products. After the metals are removed, the solution is further purified and returned to irrigate the heaps.

Three of Finland’s mineral processing technology suppliers have announced securing contracts from Talvivaara Project. On July 12, 2007, Larox said it had received the biggest single contract in the company’s history at €10 million and in the following month of August, Outotec announced it would supply metals recovery technology valued at approximately €40 million. The Larox contribution will include several Pannevis horizontal vacuum belt filters with auxiliaries. Delivery will be in two phases during the years 2008 and 2009.

Outotec’s scope of delivery covers metals recovery technology, including reactors and thickener technology, in which nickel, copper, zinc and cobalt are precipitated from the pregnant leach solution to produce saleable metal products. Technologies will be commissioned in two phases; the first phase is expected to be commissioned in October 2008 and the second phase in autumn 2009. “The Talvivaara nickel project is an important step in the history of bioleaching. Talvivaara’s bioheapleaching technology has its origins at Outotec’s Pori research center in Finland and now this technology will be in commercial use and allow economical beneficiation of the lowgrade nickel deposits,” according to Outotec’s CEO Tapani Järvinen.

Metso Automation is supplying the main plant’s automation and control system, with deliveries segmented into four phases, starting in January 2008.

The Talvivaara production plant’s metals recovery lines, side processes, crushing and conveying operations and pumping units will be monitored and controlled by a Metso metsoDNA CR automation and information system from a single, central control room. The automation system, intelligent motor control centers and frequency converters will be linked with Profibus DP, while field instrumentation will be mostly based on Profibus PA.

Pipe Dream—or Nightmare?
The Talvivaara project will employ a leaching method new in Europe, requiring huge lengths of durable piping. KWH Pipe was selected to supply the piping systems for the installation.


The piping being installed at Talvivaara is sized to handle high volumes of leach liquids.
The largest pipe diameter being used is 1,200 mm.
 
“This method is used a lot in South America, and to some extent in Asia. This project is unique in the Nordic countries, and I am not aware of a similar one elsewhere in Europe either,” said Lassi Lammassaari, general manager of mine and infrastructure for Talvivaara Project.

The primary unknown factor is the effect that the chilly climate will have on the process. However, the process is already being used successfully at an altitude of 4 km and at below-zero temperatures in Chile.

“In our test area, the heap has retained its heat well, and freezing temperatures will not bring the mine to a halt,” Lammassaari said.

KWH Pipe is currently installing collector pipes which will be buried under the primary and secondary ore heaps. Vesa Ervasti, KWH Pipe’s district manager for northern Finland, has been involved in the project for several years.

“Understanding the new leaching method and the process as a whole requires constantly updated expertise and technical know-how. Fortunately, that is what we have,” Ervasti said. “The sheer amount of piping required for this method is so enormous that when I drew up the first calculations I thought that I must have misplaced a decimal point somewhere.”

According to Lammassaari, the site places extreme demands on the materials.

“The material requirements for the pipes are strict, because the fluid that runs through them is corrosive. We decided on polyethylene, which is highly acidresistant. We will need thousands of kilometers of piping all told,” he said. “We have had significant input from KWH Pipe experts from the very first.”

The primary ore heap at Talvivaara mine will measure 800 m across and 2,400 m long. At its maximum, it will contain a 22.5 million mt of crushed ore.

“It is a massive project and requires quality that can be relied on from all the materials used. We are delivering pipes, fittings and chambers to the construction site. We have also invested in new welding machines to make the project selfcontained,” said Ari Vaarala, operations manager at KWH Pipe.

The leaching system requires a huge quantity of KWH’s Weholite pipe; the largest pipes are 1,200 mm in diameter.

“Come hell or high water, every step in the process will be carried out with utmost care,” said Vaarala. “The KWH Pipe installation team has been working on site since mid-August. There are two KWH Pipe fitters there together with excavation contractors, and their supervisor is also from our company.”

Vaarala noted that KWH Pipe is always prepared to commit more staff to the installation work if necessary.

As featured in Womp 08 Vol 4 - www.womp-int.com