Mining stocks are in demand after an upbeat trading statement from Kazakhstan's ENRC.Chiefs at ENRC are "pleased" with progress during the first quarter and say the recovery in demand, especially in China, continue to give it confidence for 2010.Revenue for the three months to 31 March "increased significantly" on the year before, reflecting higher production and sales volumes in the ferroalloys and iron ore divisions and the addition of copper and cobalt sales.The stock is among the best performers in the FTSE 100. Fellow mining giants BHP Billiton, Xstrata and Rio Tinto are also strong.Ground engineering specialist Keller leads the construction and engineering sector lower after it warned problems in the US would hit its results hard this year."A continued deterioration in the US construction market has led to a further reduction in volumes in our US businesses. More importantly, the resulting more intense competitive environment has led to increased pressure on margins, which is likely to continue for the remainder of 2010," Keller said.Top performing sectors so far todayFixed Line Telecommunications 1,917.95 +7.68%Mining 21,937.85 +2.16%Forestry & Paper 4,830.95 +1.70%Oil Equipment, Services & Distribution 17,864.33 +1.52%Health Care Equipment & Services 3,665.63 +1.35%Bottom performing sectors so far todayConstruction & Materials 3,491.90 -4.42%Banks 4,884.41 -0.72%Aerospace and Defence 3,356.38 -0.43%Electricity 6,338.74 -0.42%Insurance (non-life) 1,370.13 -0.39%