The blasting technique is currently the basic excavation method in Polish underground copper mines. Applied explosives are usually described by parameters determined on the basis of specific standards, in which the manner and conditions of the tests performance were defined. One of the factors that is commonly used to assess the thermodynamic parameters of the explosives is the velocity of detonation. The measurements of the detonation velocity are carried out according to European Standard EN ­13631-14:2003 based on a point-to-point method, which determines the average velocity of detonation over a specified distance. The disadvantage of this method is the lack of information on the detonation process along the explosive sample. The other method which provides detailed data on the propagation of the detonation wave within an explosive charge is a continuous method. It allows to analyse the VOD traces over the entire length of the charge. The examination certificates of a given explosive usually presents the average detonation velocities, but not the characteristics of their variations depending on the density or blasthole diameter. Therefore, the average VOD value is not sufficient to assess the efficiency of explosives. Analysis of the abovementioned problem shows, that the local conditions in which explosives are used differ significantly from those in which standard tests are performed. Thus, the actual detonation velocity may be different from that specified by the manufacturer. This article presents the results of VOD measurements of a bulk emulsion explosive depending on the diameter of the blastholes carried out in a selected mining panel of the Rudna copper mine, Poland. The aim of the study was to determine the optimal diameter of the blastholes in terms of detonation velocity. The research consisted of diameters which are currently used in the considered mine.

On the basis of induction heating, radiation heating and liquid nitrogen refrigeration, high-temperature, medium-temperature, normal-temperature and low-temperature heating/refrigeration furnaces were designed, respectively. An apparatus with a wide temperature range and high accuracy applied to test oxidation resistance of materials has been developed based on the thermogravimetric method and the heat transfer principle. The apparatus consists of four heating/cooling systems, a specimen fixture positioning unit, a laser positioning unit, vertical and horizontal moving guide rails, and a high-precision weighing balance. The apparatus, based on the thermogravimetric method, is able to test oxidation resistance of materials. In the test, the temperature range was −180∼3000◦C (the highest temperature is determined by material properties). The temperature control accuracy was ±5◦C. The accuracy of on-line weighing was ±0:1 mg. The measurement uncertainty was 0.2 mg. Compared with other relevant devices, this apparatus has its own advantages: simple operation, wide heating/cooling temperature range, sufficient specimen heating, high sensitivity and precision, and short heating/cooling time. The experimental results show that the developed apparatus presented in this study not only can be used for isothermal thermogravimetric tests, but also for thermal cycling tests and multi-step oxidation tests. With the effective integration of multiple heating apparatus and refrigeration apparatus, the apparatus breaks through the limitations of the heating/cooling temperature range of the existing devices, accomplishes the high-precision oxidation resistance test of materials in a wide temperature range, and will play a great role in improving the research of materials.