在英明领袖华主席抓纲治国战略决策指引下,通过深揭狠批“四人帮”破坏安全生产,破坏防尘工作的罪行,鞍钢大孤山铁矿和长沙矿山研究院组成的以工人为主体的,矿内外三结合牙轮钻机除尘试验组,经过二年多的反复研究试验,克服重重困难,终于在今年四月研制成牙轮钻机四级干式除尘装 Guided by the strategic decision of wise leader Chairman Mao Zedong and the rule of the country, Anshan Iron and Dagushan Iron Mine and Changsha Institute of Mining have taken the workers as the main body through deep exposing and severely criticizing the “Gang of Four” for sabotaging safety production and damaging dust-proof work. After three years of repeated research and experiments to overcome the numerous difficulties, the dust test group of three-in-one combined cone drills was finally developed in April this year into a four-stage dry dust removal rig