** Shares of Himile Mechanical Science and Technology Shandong Co Ltd SZSE:002595 drop 6.4% to 58.4 yuan, their lowest since May 7
** Stock set for the biggest one-day pct drop since April 7
** A large explosion took place at a chemical plant in China's eastern province of Shandong on Tuesday, state media said, but gave no immediate details of casualties
** Emergency services swung in to begin rescue and treatment efforts after the blast, just before noon in the workshop of Shandong Youdao Chemical, broadcaster CCTV said
** Shandong Youdao Chemical is owned by Himile Group, which also owns Shenzhen-listed Himile Mechanical
** The blue-chip CSI 300 Index SZSE:399300 eases 0.5%, the Shanghai Composite Index SSE:000001 slips 0.2%