premise: A coal mine blast has killed 16 miners in southwestern China, the latest disaster to strike the country's notoriously dangerous mining industry, state media said Saturday.
  The gas explosion took place early Friday morning at the Zhonghe Coal Mine in Shuicheng county, Liupanshui city, Guizhou province, while 31 miners were working in the shaft, the China News Service website reported.
  In another mine accident, 42 workers remained trapped in a flooded coal shaft in central China's Henan province, the state-run Xinhua news agency said Saturday.
  The news came as the death toll from last Sunday's explosion at the Dongfeng coal mine near Qitaihe in the northeastern Heilongjiang province rose to 169.
  China's mines, many of them illegal, are considered the most dangerous in the world, especially in recent years, with demand for raw materials escalating to help fuel China's rapid economic growth.
   Why is the demand for raw materials escalating in China?
hypothesis: A coal mine blast