Nickel prices have rallied overall this year, so it's no surprise that nickel mining companies have been working hard to take advantage of the market. Even considering that the base metal has come down from its earlier highs, its performance is still well above price levels at the start of 2014, and nickel is expected to continue rising. Here, Nickel Investing News takes a look at five companies that have seen significant share price rises this year and what they've been up to recently. Royal Nickel (TSX:RNX) First up is Canada's Royal Nickel. The company has gained over 66 percent this year, and is focused on its 100-percent-owned, development-stage Dumont project in Quebec's Abitibi Region. To be sure, Royal Nickel has been busy advancing the permitting process for Dumont; the company saw its environmental and social impact assessment for the project published in April, and in May it arranged to begin detailed engineering work. Furthermore, Royal Nickel has been busily snapping up interests in other projects. It entered an agreement to acquire 56 percent of True North Nickel and the West Raglan nickel project in June, and in August Sudbury Platinum, which Royal Nickel holds an interest in, purchased a 100-percent interest in CaNickel Mining's (TSX:CML) Aer-Kidd project. Incidentally, CaNickel is up 95 percent year-to-date, and has gained roughly 83 percent since August 11, when Sudbury Platinum announced plan to exercise its right of first refusal to purchase Aer-Kidd. PolyMet Mining (TSX:POM,NYSEMKT:PLM) PolyMet is currently focused on its development-stage NorthMet nickel-copper-precious metals project, located in the historically mined Duluth Complex in Minnesota. In March, the company successfully responded to comments on a supplemental draft environmental impact statement for NorthMet, and received a significantly improved rating from the US Environmental Protection Agency.