Field Testing and Analysis of Blasts Utilizing Short Delays with Electronic Detonators

The emergence of electronic detonators as viable products for use in production mine blasting has enabled mining professionals to rethink the traditional blast design methodologies that pertain to timing. This proposal seeks funding to determine and analyze the performance of commercially available programmable electronic detonators against conventional delay systems at the same location in a surface coal mine. The major portion of the proposed work, (fifteen) field blasts will be monitored and analyzed via high-speed video, VOD monitoring, and seismic analysis. The field blasts will use three types of detonators selected for short" delays between holes in the front row of the blast. Short delays pertain to the range of 3 milliseconds for the two electronic systems and the minimum manufactured delays for the non-electric system. Recent blasts performed by Nelson Brothers, LLC. in West Virginia and Kentucky have utilized similar timing scenarios for electronics and have experienced positive results in both productivity and blast vibrations. With timing intervals this low, accuracy is extremely important to prevent holes firing out ofsequence. In many ways, electronic detonators can allow great advances in productivity, cost effectiveness, fragmentation, and safety. There are a number of commercially available systems that enable users to program delay times according to design decisions. The systems typically allow for programming one-millisecond intervals over a broad range. Limited information is available concerning the accuracy of modern pyrotechnic delay based detonators much less electronics. In 1985, the Bureau of mines completed a study of three manufacturers' electric millisecond delay detonators (Bajpayee, 1985). This is the most recent extensive study performed on detonators, which unitized pyrotechnic delays, from numerous manufacturers. In order to facilitate confidence in the field testing, accuracy testing of electronic detonators used in the field tests will be required. This is especially true since short delay periods will be utilized. In addition, limited testing of non-electric detonators will be necessary for comparison purposes similar to the field tests. This research also aims to determine the accuracy of two specific systems of commercially available electronic detonators, and one non-electric shock tube systems. Each of the three systems of detonators will be tested at the minimum delay available, at mid-range, and at the highest delay available. As a quality control measure, three separate date codes will be tested. Groups of 20 for each system, delay, and date will be tested. This test series will subsequently consist of (180) detonators per system for a total number of (540) detonators. The primary objectives of the proposed research include: 1. Observation and an~lysis of surface coal mine blasts that utilize short delay intervals «3 milliseconds between charges in electronics scenario) and comparison of the results to conventional delay designs at the same location. 2. Determination and documentation of the accuracy of delay times in two specific programmable electronic detonator systems in comparison to the desired time programmed into the detonators. 3. Determination of accuracy in delay times for a select number of non-electric shock tube type millisecond delay series detonators.