A comparative analysis of some recent mining practices in the Tri- State Mining District

The Tri-State District, encompassing contiguous corner portions of Southwest Missouri, Southeast Kansas, and Northeast Oklahoma, has been, for many years, the leading zinc producer of the United States. However, rising labor costs and decreasing grade of ore reserves have meant that many of the mines gradually have become marginal in the economic character of their operations. In an attempt to counteract these adverse effects, steps were taken to attain lower cost mining methods, and mechanization has been introduced over a period of years. Further, the research program of the Eagle-Picher Company, the leading producer of the district, has been accelerated inasmuch as it became expedient to open new mines and to rehabilitate some abandoned properties under th stimulus of war demand. Clarke, recently, has given a concise account of the modified mining methods used and therein came the first hint of a radical change in drilling practice. The old method of drilling using a post (or column) was expensive not only of effort but also of time. In overcoming this disadvantage two main problems immediately were present; first, that of achieving increased production at the time of manpower shortage because of the war, and second, to accomplish better utilization of the drilling machines, i.e., increased footage per drill shift, and attendant reduction in cost. It was under these conditions that a portable drill carriage mounted on a caterpillar tractor chassis was developed to supersede the old method of mounting the drill on a post. The machines are called jumbos . An examination of the records (Table I) of the Eagle Picher Mining and Smelting Company, and their interpretation (Plate I), indicated that a definite improvement in production has resulted since the introduction of the caterpillar jumbos. This study of drilling operations was undertaken as a comparative analysis of the old and new methods to determine the reasons for the improvement. In addition, the transportation systems in use were analyzed to determine how far they are fitted to cope with the increased unit production from the jumbos --Introduction, page 1-2