Vol 13 Iss. 3

On October 2, 1940, after a prolonged and serious illness, the head of the Mine Surveying Department of the Leningrad Mining Institute, Doctor of Technical Sciences, Corresponding Member of the USSR Academy of Sciences, Ivan Mikhailovich Bakhrin, passed away. In 1909, upon graduating from the St. Petersburg Mining Institute, I.M. Bakhrin became the first of the assistant professors at Russia's first department of mine surveying art, which was founded and headed by one of the most popular professors of the Mining Institute, V.I. Bauman. For a long time, I.M. Bakhrin served as Dean of the Mine Surveying Faculty and later of the Mining Faculty of the Institute. In his scientific works, he developed a number of important issues in mine surveying and magnetic prospecting. Ivan Mikhailovich was not only a prominent scientist but also a talented educator. All the key methodological documents on mine surveying education in the USSR were created with his direct participation and under his leadership.

The study of schistousity of rocks of organic (more correctly — mixed) formation, such as a solid kaustobiolithes, has been shown a known community of its formation with the schistousity of a clastic rocks. This community greatly depends upon the irregularity of bearing and sedimentations of organic, as well as inorganic material, i. e., upon the difference of material composition of layers. Though, equally with this schistousity of coal, there are specific particularities attributed only to the combustible minerals. They are connected with a considerable decrease of material and volume, as well as condensation at the time of humification and carbonization, beginning from a green peat up to the antracite; corresponding cypher of this variation could be estimated as about 5-7. Horizontal deposition of a vegetable remains is partly connected with this phenomenon. The schistousity of allochthonous and autochthonous coal should be in a certain degree distinguished in the way that it is more pronounced in the first one: though this question is not yet settled. The schistousity of sapropelites has, naturally, some difference, as far as it is not connected with the conditions of deposition at the place of growth but “under place”, i. e. by means of a falling out from the suspended position according to the law of falling of small particles. As far as leptobiolites is concerned, they have a tendency to get a massive constitution. Comparing the schistousity with the other physical properties of coal, we see that it is connected with the same factors as with a nature of coal, quantity of ashes and a degree of carbonization. Schistousity, its character, formation and a degree of development are closely connected with the conditions of formation of coal itself. These factors can be used as a substantial material for the interpretation of coal.

In determination the limit of open pit and underground mining technical and economical factors are to be considered. The ratio of overburden and waste rock stripped to the ore reserve is the principal criterion of utility of the open pit mining. Many attempts were made to give the mathematic solution of this problem, but complicated formulas and mistakes in mathematic interpretation prevented from using it in practice (see Part 3). The purpose of this article is to give the solution of this problem on the base of determination of the most profitable open pit. It is possible to give the general formulas (9) and (10) showing the expenses concerning the mining of the deposit by two variants: a part of deposit (A) is mined by open pit and another part (C) by underground method (Fig. 2); all tonnage of deposit (A + C) is mined by underground method. In the part 8 of this paper a few examples of this method are illustrated.

As indicator electrode at the potential titration of diluted solution of the xantate Ag—Ag₂S and mercurial electrode were tested. The most convenient for analysis of xantate solutions not including the sulphide sulphur is a mercurial electrode. The presence of a caustic alkali soluble carbonates, sulphates, sulphites and thiosulphates does not effect the result of titration. The method was worked out as to the potential metrical titration of xantates and soluble sulphides in diluted solutions at their compatible presence. The method consists in determination of the sum of sulphide and xantate by means of potential metrical titration by sublimation with mercurial electrode and determination of sulphide by means of potential metrical titration by the double cyanide of Ag at the Ag—Ag₂S electrodes. On account of the simplicity and dependability the recommended method of analysis could be applied not only in the laboratory conditions but at works for to control the process of sulphidisation of oxidized ores.

The question of the dependence of local resistance coefficients k on the roughness of the walls of air ducts is one of the little studied issues of practical aerodynamics. Most aerodynamics courses provide values, sometimes very detailed, of coefficients k for a number of local resistances – bends, sudden contractions and expansions – but usually do not indicate how to use these coefficients: whether to take them as constant, independent of the roughness of the walls of the air duct, or, conversely, to consider them as variable quantities related by some dependence to the coefficient of friction on the walls of the air duct. The work done by the authors made it possible to clarify the relationship between the coefficients of local resistance k and the coefficients of friction α of air on the walls of the air duct. The previously accepted dependence turned out to be incorrect and must be replaced by another (see the article). The turning resistance coefficients given in various courses should be increased for rough concrete support by 8–10% and for workings supported with staggered door frames by 25–30%. The correctness of formulas (11) and (12) for other types of local resistance requires verification.

Orientation of mines is one of the most labor-intensive and responsible tasks of the surveying service. The performance of magnetic orientation does not require stopping the mine shaft either during the preparation period or at the time of production. Magnetic orientation has a number of important advantages (see article). The accuracy of magnetic orientation, as is known (at this stage of study of this issue), does not depend on the depth of the mine. In addition, all sources of errors (in determining azimuth) that accompany geometric orientation are eliminated. Practice in the performance of magnetic orientation here and abroad shows that if the work is carried out thoroughly and all required conditions are met, magnetic orientation guarantees an accuracy of 1'–2' and even higher. This is also evidenced by the results of our work described below. In our work, we make an attempt to analyze some of the issues raised above, based on an analysis of field observations we made in 1937 at the Novaya Golubovka mine.

In places of crossed or conjugate workings, the magnitude of vertical rock pressure, as is known, increases significantly. In this case, it is not possible to use the usual method of replacing the intersection of workings with a working of an equivalent span. Shape change theory is used to determine the magnitude of this rock pressure. Equations (8) and (10) represent the equations for changing the shape of the column in the case of straight or inclined intersections of shaft structures. The maximum change in the shape of the support angle is expressed by formulas (4) and (5). The equivalent width of the intersection of shafts is determined by formulas (9) and (15).

Crystal identification tables showed that five crystals of the mining museum N 110/1-4 and 110/8, which were stored as rutile, do not differ from cassiterite crystals. It is also known that these cassiterite crystals were formed from the Atlyan placers of the Southern Urals. When examining the Eremeevskaya collection of the mining museum, cassiterite was also discovered on a shelf from the Atlyan placers. Since no tin deposit has yet been discovered in the central regions of the USSR and the geological conditions in the Atlyan River district are favorable for the formation of cassiterite deposits, detailed prospecting work must be undertaken in this district.

Post-ore faults in the Sadonskoye deposit are accompanied by white and black clays. In the specialized literature, a paste or vein clay (gouge) is a soft, clay-like material that occurs as a rim between the vein and side rocks. The paste is usually formed by crushing and abrasion of ore, or side rock, or both together. Previous researchers considered the black clay of the Sadonskoye deposit to be clay shales captured by the fault (Domarev, Skakovsky). As a result of geological, petrographic and mineralogical studies, black clay appears as ground rock, crushed by the western fault, the source material for which was the side rocks of the ore body and the ore body itself.