Vol 10 Iss. 3

The strength calculation of a rope is in practice somewhat conditional. Specifically, one proceeds from the ratio of the breaking load to the static load, which is called the safety factor and whose minimum value is established by safety regulations for hoisting. Having set this factor and determined the number and diameter of wires with its help, a verification of the safety factor is then carried out, partly taking into account the actual stresses in the rope. However, since the latter are not fully accounted for, such verification cannot provide a sufficiently clear picture of the actual value of the safety factor. In the present study, we confine ourselves to small lifting heights, reducing the problem to the integration of an ordinary third-order differential equation.

Systematic index of articles

Starting from the consideration of the oscillating inertia screen as a system with three degrees of freedom, a system of Lagrange's differential equations is formed, and the small terms depending on the translatory and Coriolis acceleration of the inertia weight are omitted. The design of the screen in which the resulting equations become independent and the torsional vibrations almost disappear is described. In order to amplify the vibrations of the screen perpendicular to its plane, the system should be tuned to resonance with these vibrations. Assuming that the oscillations of the inertia screen take place perpendicular to the plane of the screen, the motion of an inelastic particle jumping along the screen is analyzed, and the resonance conditions between the screen oscillations and the particle jumps are determined. It turns out that the screen of slate rock "resonance" also quite well satisfies the condition of this second resonance. The condition for the existence of complete resonance is investigated, and the motion of inelastic particles under complete and incomplete resonance is analyzed. Formulas are given for calculating the efficiency of the screen and the sum of the kinetic energies of all impacts of a given particle during its motion along the screen under complete resonance. For incomplete resonance, an example of numerical calculation is provided.

When calculating mineral reserves in deposits, instead of the volume of the actual ore body, the volume of a body that is sufficiently close to it and has the correct geometric shape is usually calculated. An unsuccessful choice of such a geometric body can lead to a significant decrease in the calculation accuracy or greatly complicate the calculations. In the practice of calculating reserves with such exploration data, the volume of the explored body was sometimes calculated as the volume of a cone with a base equal to the contoured area on the horizon, and with the apex at the point where the drill well exits the deposit, without taking into account the thickness of this latter. The calculation made in this way gave reserves below the minimum determined by exploration data, and the discrepancy reached a significant value of several tens of percent. Below are methods for calculating the volume of a conoidal body, which can serve to calculate the reserves of a part of an ore deposit limited by a contoured area at a certain horizon and cut by a drill hole at depth.

The present work aimed to determine the oxidizability of lake sapropels by various oxidizing agents in connection with the very easy oxidizability of balkhashite by nitric acid, as shown in our earlier work. The investigation carried out showed the analogous behavior of the mentioned sapropel material towards these oxidizing agents, both with regard to the quantity of the oxidation products and with regard to their quality. In both cases, the substances obtained are mixtures of higher carboxylic acids and their easily stiffening derivatives. The applied significance of this work is the use of the obtained oxidation products as flotation reagents. The investigations carried out showed their high flotation power against sulfide as well as oxide ore minerals. The newly discovered properties of sapropelic material — its easy oxidizability under certain conditions with the formation of technically valuable products in large quantities — open up new possibilities for the use of these interesting compounds for the benefit of industry, since they are widely distributed and occur in many places of the Soviet Union as thick deposits of new and old geological formations.

The article sets out a reasonable hypothesis of the causes of mineral flotation. Its main principles are as follows: Insignificant flotation of "sulfide" minerals is due to the formation of halogen oxidation products on their surface, which react with collectors to form stable oriented films of the corresponding organic sulfide compounds of heavy metals, which are inseparable from the substance of the minerals. Cleavage of complete collection products from the surface is possible due to oxidation or as a result of intramolecular rearrangements, especially in the presence of excess collector. The reason for the strong floating of "oxide" minerals is the formation on their surface of unstable reaction intermediates between substances in the mineral and the collector. The effectiveness of sulfidization of oxidized minerals is due to the transformation of their surface into the corresponding hemisulfides, which are able to react with collectors. The article compares and discusses modern theories of the flotation ability of minerals.

In the present paper an attempt is made at ascertaining an entirely attainable technical efficiency of excavators, taking into account the best achievements of practice and analyzing all the possibilities of excavators. Investigation is directed along the lines of constructive possibilities of excavators, methods of utilizing them, and working conditions. As a result, the possibility of raising the existing indices and established norms is proved. Though the conclusions arrived at take into account the indices of real practice, nevertheless they have to be verified under the working conditions of several undertakings.