In June 2012, while passing through Sweden on my way to a magnets conference in Finland, I made a short detour to visit the Woxna Graphite Mine, the flagship graphite project of Flinders Resources Ltd. (TSX.V:FDR) and located at the site of the company’s Kringel graphite deposit.
The previously operating Woxna mine is located in central Sweden, approximately 5 miles from the town of Edsbyn. The capital Stockholm lies around 190 miles to the south.
Per the September 2012 NI 43-101 compliant mineral-resource estimate for the Kringel deposit, at a 7% graphitic carbon (Cg) cut-off grade, 1.5 Mt of the resource is at the Measured level @ 10.4% Cg, and 1.1 Mt is at the Indicated level @ 10.7% Cg. This results in an estimated 273 kt of Cg present in the deposit. Indications are that there is a significant fraction of the more desirable large-flake graphite at this site.
The Kringel deposit is actually one of four graphite deposits that form part of the Woxna graphite project, named after a local river and which is wholly owned by Flinders through its Woxna Graphite AB subsidiary. The Woxna mine is fully permitted with much of the previously operating mine and plant infrastructure still in place. Woxna Graphite AB produced some 13,000 tonnes of graphite per year at the Woxna mine, from 1996 until 2001, when the mine was closed and put on care and maintenance due to falling graphite prices.
The graphite produced included coarse (+160 µm) , medium (+75/-160 µm) and fine (-75 µm) flake materials. Size distributions within the graphite produced were typically 40% @ +160µm, 28% @ +75/-160µm and 32% @ -75µm (all at up to 94% C).
Getting to the Woxna mine site was straightforward. After taking the train north from Stockholm to Söderhamn, I was met at the train station by Folke Söderström, Managing Director of Woxna Graphite AB. We took a 90-minute drive west towards Edsbyn and the mine site, and along the way we had the chance to discuss the Woxna project, its history and its place within the local community.
You can see photographs taken during the visit, in the galleries below (click on each image to enlarge it).
The mine site itself consists of an open pit, a processing facility and a tailings storage facility from past production. In addition to getting the mine back up and running, Flinders has invested resources since acquiring the project, to upgrade the historical graphite resource estimates, resulting in the initial NI 43-101 compliant estimates summarized above. My visit to the site coincided with a visit from Geoffrey Reed, a consulting geologist who is the independent Qualified Person for the Woxna project, who was also able to offer insight into the geology of the project.
The graphite mineralization at the Kringel mine occurs in two types. The A-type contains higher grades of graphitic carbon; the B-type has lower graphite content, and has relatively high concentrations of sulfides. The latter is more challenging to process because of the impurities present, and most of it was historically stockpiled during mining. Mr. Söderström indicated that the company plans to develop processes to be able to use B-type material. According to the resource estimate, the Kringel resource was drilled within an area that was approximately 1,200 m in length, by 100-200 m in width. Mineralization in the deposit was intersected by all drill holes, is present to at least 150 m below ground and is open at depth. The thickness of the mineralization was typically greater than 10 m, but varied between 5-25 m. Mineralization at Kringel remains open along strike too.
The host rocks in the vicinity of the Kringel deposit contain sulfides, meaning that they are naturally acidic. Indeed, initial measurements from the tailings pond indicate pH levels of 3-3.5, a significant level of acidity; the mine pit is partially filled with groundwater, with initial pH levels of 5-4.5. Mr. Reed commented that pH and water management for the project, both in terms of processing the graphite once mined, and subsequent safe disposal of waste materials, will be particularly important for the project. In the vicinity of the tailings pond are clarification ponds that were used previously to help control the pH levels of the water subsequently used in the processing facility.
The bottom of the pit is approximately 45 m below the adjacent surface. Recent calculations indicate that there is approximately 75 kt of A-type mineralization down to approximately 65 m below the adjacent surface. Mr. Söderström said that he planned to de-water the pit this coming fall (autumn), so that the company could get a better idea of how the pit was mined previously, and to begin new mining. The pit contains approximate 200,000 cubic meters of water. He also commented that they were looking to use strip and sterile areas on the property as feedstocks for road and berm construction, to reduce the cost of trucking in such materials.
Since my visit to the Woxna mine site, dewatering of the pit has begun. The water in the mine has been conditioned via the addition of lime, to increase pH levels and to ensure that it complies with the conditions of Kringel’s water discharge permit. Recent testing has confirmed that the water is within specification and so pumping of the water from the pit has now commenced.
The tailings areas from past mining are contained by two walls, known as the upper and lower dams. It is likely that some remediation work will be required for the tailings area, including sealing or otherwise preventing acidic run off from entering the clarification pond (known as acid mine drainage). There is some evidence that the tailings dams have leaked at some point, meaning that pH levels must be managed before water can be discharged from the mine site (in similar fashion to de-watering the pit). Characterization work at these tailings sites is ongoing, so that the geologists and mining engineers have a better idea of what they are dealing with, and so that they can satisfy environmental permitting requirements into the future.
Also on-site during my visit was Elin Ryosa, a geologist originally from the area, and who is working as the exploration and mine geologist for the project. She explained that the local geology at site shows development of trace to massive graphite in high-grade metamorphosed, metasedimentary and metavolcanic host rocks, which have been metamorphosed to sillimanite grade and intruded by felsic units, ranging from alkali pegmatite to granite. At Kringel, the geology is dominated by steeply-dipping, calcareous quartz-rich meta-tuff, with interbedded metasedimentary units and cross-cutting pegmatite. Two discrete tabular zones of graphite mineralization are developed and trace pyrrhotite (an iron-bearing mineral) is associated with the mineralised zone, its foot wall and hanging wall.
We were able to go out into the area surrounding the pit, where drilling was being undertaken for the mineral-resource estimate. Ms. Ryosa commented that in continuous zones the diamond drilling rigs could produce up to 25 m of drill core per shift, meaning that a single drill rig could complete a hole every day or so, depending on conditions. The area being drilled was quite boggy when we visited and small clearings have to be made in the forest to complete the work. The region of interest around the Woxna mine has a covering of moraine deposits from the last Ice Age that can be several meters thick in places. Because graphite and pyrrhotite are good electrical conductors, modern geophysical techniques make it fairly straightforward to detect the presence of graphite to significant depths.
We then took a look at the existing processing facilities on-site at the Woxna mine. When in production, Mr. Söderström said that the initial mining and crushing was historically undertaken by a third-party contractor, with the material being fed into rod and ball mills for subsequent grinding. The coarsest flake material was subsequently removed by flotation as well as spiral and vibratory tables for gravimetric separation.
The rest of the material went through additional cycles of grinding, milling and flotation. These materials were then filtered and dried, before being sieved into the coarse, medium and fine flake sizes described above, and then bagged for shipping. The original crushing equipment was removed from the facility when the mine closed, but otherwise all of the machinery from grinding to final packing remains in good order.
Mr. Söderström indicated that at some point in the life of the original mine additional milling equipment was acquired in order to better optimize the processes being used. However, restricted funds due to the low graphite prices at the time, meant that numerous opportunities to improve purity, large-flake recoveries and to reduce operating costs were unable to be pursued.
Interestingly, at the time of my visit there were approximately 500 t of previously processed graphite that had not been shipped before the original operations closed. Mr. Söderström indicated that the company was in the process of characterizing these stocks, with a view to selling them to end customers as a means of both generating some revenues and cleaning up the site. Since my visit, processing at the Woxna mine has been restarted, and production of graphite from these stockpiled materials is now underway. The entire supply has apparently been sold to customers in Germany.
Mr. Söderström said that the company has developed a good rapport with the people who live in the vicinity of the Woxna mine, and the other landowners. One of the first things that Flinders did on acquiring the project was to meet with the local residents, to introduce the management team, to explain what the plan was for the mine, and how that might benefit the local community (in contrast to the low-key approach taken by the previous owners of the mine). There is a local cooperative for landowners, which among other things organizes local road maintenance. As previously mentioned, the by-product of the mining activities at the Woxna site is suitable for road construction, and so could be used on local roads. It is important for Flinders to engage with this group on topics such as new water pipelines, road upgrades and so on. An example of such projects is a proposed new road to connect the Woxna mine directly to the main road, bypassing the local community so that vehicles coming to and from the mine will not disturb the local people.
Speaking of water; the Woxna mine draws its power from a hydroelectricity power station on the Woxna river, and will continue to do so when back in operation. This station was built before the original mine was opened, to provide power to the entire district, which includes a number of lumber mills. Some of these mills are able to provide heating to the local district through the effective use of waste water, lowering heating costs. Mr. Söderström commented that the company might consider installing a wind turbine on site, or using forestry waste in boilers, to reduce energy costs.
Forestry companies own most of the land surrounding the Woxna mine; timber production has been the dominant industry in the region for many decades. Flinders is interested in acquiring some of the land surrounding the mine as part of the further development process, and to date there have been no obstacles to pursuing that course of action. The value of such land is typically based on the value and quantity of the timber that could be harvested.
The Woxna mine is located less than 10 miles from a rail line and the port of Söderhamn on the east coast of Sweden is 50 miles to the east. Getting graphite products to market, therefore, should present few logistical issues, as evidenced by sales of graphite in the past from this facility.
After visiting the Woxna site, I believe that Flinders is well on its way to getting this project back up and running, with relatively low capital expenditures required, compared to green-field graphite projects elsewhere. Since my visit, the company published the NI 43-101 resource estimate for the project and started reprocessing the aforementioned stockpiled graphite. They have also appointed Craig Griffiths, an experienced mining engineer, as General Manager for the mine, with him starting his work there later this month.
My thanks go to Martin McFarlane, President & CEO and his team, for organizing the logistics of my visit, and to Folke Söderström and his on-site colleagues for hosting me on the visit.
Disclosure: at the time of writing, Gareth Hatch is neither a shareholder of, nor a consultant to, Flinders Resources Ltd. (Flinders). Neither he nor Technology Metals Research, LLC received compensation from Flinders or from anyone else, in return for the writing of this article.
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