Having increasingly tightened geological and mining conditions in which the extraction of copper ore deposits in Poland is conducted, ensuring effective and safe mining is presently becoming a key task and a significant challenge for mine operators, mainly in the field of ground support systems being the equivalent for the new geological/mining conditions. As one may expect, these conditions shall be characterized by higher values of the primary stress tensor elements as well as the lower deformability and higher strength of the rock mass surrounding the copper ore body. T his means that in the near future, the rock bursts problem will become one of the most important issues deciding on the economy and safety within the newly developed mining areas. T herefore developing a novel effective ductile ground support systems which could be able to control the rock mass movement in squeezing and burst-prone rock conditions is recommended. T his type of requirement may fulfil only ductile or, in other words, the kinetic energy-absorbing systems, which permit slowing down a movement of violently ejected rock blocks. T his paper’s objective is to present the idea of the development of a new type of an effective and low cost ductile resin anchored rockbolt system with smooth and of the square cross-section steel rod is formed in coil shape of different pitch. T he developed bolt prototypes have been tested underground in the G-11 section of the Rudna mine. Results of the pull-out tests, involving different bolts’ shapes and different sliding materials set on the rockbolts’ rods, have proved those bolts’ efficiency as an element of the ductile support system.

The study was intended to determine the effect of the input condition of the 17-4PH steel on the microstructure, mechanical properties and stress state of welded joints. The steel adopted for testing was in the solution condition at 1040°C, the aged condition at 550°C/4h and the overaged condition at 760°C/2 h + 620°C/4 h. Samples of 17-4PH steel, after heat treatment processed with different parameters, were electron beam welded (EBW). The microscopic observation (LM, SEM/EDS) showed that the microstructure of the weld consisted of martensite with a δ-ferrite lattice. In the heat-affected zone (HAZ), transformed martensite was found with evidence of niobium carbides. The results of hardness testing revealed the different nature of the hardness profile with the condition the material before the EB welding process. The hardness profile of the HAZ of the welded samples in the as-solution (ES2) and overaged (ES12) condition was varied (from about 340 HV to 450 HV). However, in the aged condition specimen of 17-4PH steel (ES22) showed a similar hardness level, at around 370 HV. The solution condition (ES2) had the highest strength properties R_m 1180.6 MPa with the lowest elongation A 7.6% of all samples tested. The aged welded specimen (ES22) retained high strength R_m 1103.4 MPa with a better relative elongation A 10.1%, whereas the overaged welded specimen (ES12) saw a reduction of strength R_m 950.4 MPa with an improvement in plastic properties A 18.8%. Obtained results showed a significant effect of the input steel condition on the obtained EB welded joints.

A proper description of ground motions generated by seismic and paraseismic events requires gathering data of six components of seismic waves. T hree of them, the so called translational waves, are well researched and identified. Unfortunately, until recently, the remaining three components named as rotational waves were generally estimated with the use of indirect methods based on theoretical calculations. T his was related mostly with the lack of proper instruments for the recording of rotational seismic waves. T hus, rotational waves were not fully recognized thus far. Recently, several types of advanced instruments for direct measurements of rotation were invented. Based on the measurements of strong ground motions it was indicated that the amplitude of the rotational components in close distances from the seismic source can be significantly larger than expected. Apart from this, there is still a lack of analyses considering the characteristic of rotational seismic waves generated by induced seismic events. In this paper, the results of preliminary measurements of rotational motions generated by induced seismic waves were presented. Ground movements related with mining tremors were analyzed in terms of amplitude, frequency and duration.

The problem related to the management of post reclamation dusts generated in the reclamation process of waste moulding sands with

organic binders is presented in the hereby paper. Waste materials generated in this process are products hazardous for the environment and

should be utilised. The prototype stand for the utilisation of this dangerous material in its co-burning with coal was developed and patented

in AGH in Krakow. The stand was installed in one of the domestic casting houses. As the utilisation result the transformed waste product

is obtained and its management in the production of ceramic materials constitutes the subject of the presented publication.