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Date submitted2020-06-12
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Date accepted2020-06-12
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Date published2020-06-30
Management of hardening mixtures properties when stowing mining sites of ore deposits
Underground mining is characterized by the weakening of the bearing rock mass strata competence and the accumulation of mineral waste. The full use of subsurface resources is ensured by the use of technologies with filling voids by hardening mixtures, which requires high-quality raw materials to obtain the required strength. The deficit of the binding component can be filled with the use of granulated slags of blast-furnace process, mill tailings, ash-slags and other wastes. Most often, voids are laid by mixtures with a combination of cement and a binding component. Mixtures with ash-slag additives to cement in an equivalent amount are not inferior to the strength of the mixture only with cement, especially when grinding ash-slag. The properties of stowing rock masses when using composite binding components and inert fillers are controlled by mechanical, chemical, physical and energy effects at the stages of preparation and transportation of hardening mixtures. To obtain the active fraction of cement substitutes, disintegrators are used that apply the inertia forces of materials at a high speed of rotation with an increase in high activity indicators and lower energy costs. The components of hardening mixtures can be the majority of waste from mining and related industries, which is determined experimentally in specific conditions.
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Date submitted2019-04-04
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Date accepted2019-08-04
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Date published2020-04-24
Chemical heterogeneity as a factor of improving the strength of steels manufactured by selective laser melting technology
The aim of this paper was to establish the causes of the heterogeneity of the chemical composition of the metal obtained by the LC technology. The powdered raw material was made from a monolithic alloy, which was fused by the SLM, the initial raw material was a laboratory melting metal of a low-carbon chromium-manganese-nickel composition based on iron. To determine the distribution pattern of alloying chemical elements in the resulting powder, electron-microscopic images of thin sections were combined with X-ray analysis data on the cross-sections of the powder particles. As a result, it was found that transition (Mn, Ni) and heavy (Mo) metals are uniformly distributed over the powder particle cross-sections, and the mass fraction of silicon (Si) is uneven: in the center of the particles, it is several times larger in some cases. The revealed feature in the distribution of silicon is supposedly due to the formation of various forms of SiO 4 upon the cooling of the formed particles. The internal structure of the manufactured powder is represented by the martensitic structure of stack morphology. After laser fusion, etched thin sections revealed traces of segregation heterogeneity in the form of a grid with cells of ~ 200 μm.
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Date submitted2014-12-11
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Date accepted2015-02-11
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Date published2015-12-25
Influence of the type of hardening treatment on wear-resistant materials of mining equipment
- Authors:
- V. I. Bolobov
- S. A. Chupin
For example, steel 110G13L as the material of teeth of excavator buckets, shows that the work hardening (hardening) is an effective means to increase (up to 10 times) the wear resistance of components in contact with abrasive media, such as marble, yielding the steel in a state of hard-ening of hardness. In the case of wear on the rocks (granite, gabbro) with a hardness greater than the hardness of steel, the effect of hardening has almost no effect. It was found that high-temperature thermomechanical treatment of steel 35HGSA as the material of holders of rotary cut-ters (strain at 900 С, water quenching, tempering at 230 С) leads to a substantial increase of its hardness (23 %) and durability (38 %) compared to typical heat treatment used in the manufacture of cutting tools at the factory.