(PDF) The History of Diamond Core Drilling | Roger Burt,
By providing reliable information on geological structure, average milling grades of the ore, its extent and potential tonnage, core drilling laid the foundations of the trust that was needed for the heavy investment required for working deeper, more difficult, more complex and lower grade ores that became the mainstay of the industry from the,Longyear™ Bits Put 23% More Core in the Box - Boart Longyear,Oct 30, 2017· Using patented technology, the new Longyear bits have diamonds that are chemically bonded to the matrix creating a more versatile, faster penetrating, and a longer-lived bit. The new Longyear bits retain the smooth drilling characteristics drillers prefer, resulting in more core in the box on every shift for every crew.Superior Rock Bit, Virginia MN,Rotary Drilling came to the Iron Range in Minnesota, USA in the 1950’s. In the Early 1970’s there were many different manufacturers of rotary drill bits including: Hughes Tool Co, Reed Tool Co, Smith Tool Co, Security Eng. Of Dresser Industries and Varel Int. At that time all rock bits used in mining were air bearing bits of similar design.