scholarly journals Grain size distribution of waste rock masses of Kuzbass coal strip mines

2021 ◽  
Vol 6 (4) ◽  
pp. 259-266
Author(s):  
S. O. Markov ◽  
E. V. Murko ◽  
F. S. Nepsha
Keyword(s):  
Grain Size ◽  
Rock Mass ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Fine Fraction ◽  
Waste Rock ◽  
Height Distribution ◽  
Rock Masses ◽  
Lump Size ◽  
Natural Rock

Grain size distribution as a structural characteristic of waste rock and bulk masses in the course of mining and construction works acquires quantitative values in the process of rock blasting and hauling of rock mass. Such physical-mechanical and structural-textural parameters of a rock mass, as the ultimate strength of rocks and rock mass, fracturing, diameter of the natural rock jointing, have a significant impact on the blasted rock mass grain size distribution. On the other hand, such characteristics as stability, permeability of waste rock masses largely depend on the lithology and grain size distribution of the loosened rocks composing waste rock dumps and their height distribution within a dump. The paper describes the findings of the study of the grain size distribution of waste rock masses of Kuzbass coal strip mines and the features of its spatial variations within the masses. The textures of the bulk masses and physical and technical properties of the stacked rocks were studied both at the Kuzbass waste rock sites and in laboratory conditions. The grain size distribution of the fine lump part of the dumps with the lump size up to 50 mm was investigated by sieve method according to GOST 12536–2014, and the medium and large lump part was studied using oblique photoplanimetry. The field observations showed that the bottom part of the rock dumps, dumped by peripheral bulldozer or excavator methods was composed of coarse fraction with average lump size of: d<sub>cr</sub> = 0.8–1 m, while the middle part, of rock lumps of d<sub>cr</sub> = 0.4–0.6 m, and the upper part, mainly of fine fraction with lump size of less than 0.1 m. The ratio of length, width, and thickness of the blasted rock lumps was 1:0.85:0.8, which corresponds to elongated-flattened shape of the lumps. This requires significant number of coordinates for describing the lump positions in the rock mass, as well as taking into account the moments of inertia when modeling the motion of such lumps until they reach a stable position. Up-to-date non-commercial or commercial software and corresponding hardware can be used to take into account non-isometric shape of the lumps when modeling their motion.

Analysis of grain size distribution in broken rock mass in the Oktyabrsky Mine

2019 ◽  
pp. 24-28
Author(s):  
V. P. Marysyuk ◽  
◽  
I. A. Ryshkel ◽  
A. V. Trofimov ◽  
A. P. Kirkin ◽  
...  
Keyword(s):  
Grain Size ◽  
Rock Mass ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Oktyabrsky Mine

Grain sorting effects on the formation of tidal sand waves

2009 ◽  
Vol 629 ◽  
pp. 311-342 ◽  
Author(s):  
TOMAS VAN OYEN ◽  
PAOLO BLONDEAUX
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Fine Fraction ◽  
Sand Wave ◽  
Flat Bottom ◽  
Sand Waves ◽  
Sand Mixture ◽  
Sea Bed ◽  
The Stability

A model is developed to investigate the process which leads to the formation of sand waves in shallow tidal seas characterized by a heterogeneous sea bed composition. The main goal of the analysis is the evaluation of the effects that a graded sediment has on the formation of the bottom forms and the investigation of the sorting process induced by the growth of the bottom forms. The analysis is based on the study of the stability of the flat bed configuration, i.e. small amplitude perturbations are added to the flat bottom and a linear analysis of their time development is made. For an oscillatory tidal current dominated by one tidal constituent, the results show that the graded sediment can stabilize or destabilize the flat bottom configuration with respect to the uniform sediment case, depending on the standard deviation σ* of the grain size distribution and on the ratio between the horizontal tidal excursion and the water depth. For moderate values of , i.e. values just larger than the critical value for which the sediment is moved and sand waves appear, the presence of a sand mixture stabilizes the flat bed. On the other hand, for large values of , the mixture has a destabilizing effect. In both cases the effect that a sand mixture has on the stability of the flat bed configuration is relatively small. Moreover, for moderate values of , the fine fraction of the mixture tends to pile up at the crests of the bottom forms while the coarse fraction moves towards the troughs. For large values of , the grain size distribution depends on the value of σ*. The results are physically interpreted and provide a possible explanation of the apparently conflicting field observations of the grain size distribution along the sand wave profile, carried out in the North Sea.

scholarly journals Investigating the Influence of Structure and Heterogeneity in Waste Rock Piles on Mass Loading Rates—A Reactive Transport Modeling Study

2021 ◽  
Vol 3 ◽  
Author(s):  
Katherine E. Raymond ◽  
Nicolas Seigneur ◽  
Danyang Su ◽  
K. Ulrich Mayer
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Reactive Transport ◽  
Mineral Weathering ◽  
Waste Rock ◽  
Mass Loading ◽  
Acid Rock ◽  
Loading Rates ◽  
Construction Methods

Placement methods and material availability during waste rock pile (WRP) construction may create significant heterogeneities in physical and geochemical parameters (such as grain size, permeability, mineralogy, and reactivity) and influence the internal pile structure. Due to the enormous scale of WRPs, it is difficult to capture the influence of heterogeneities on mine drainage composition and evolution. Although laboratory- or field-scale experimental studies have provided much insight, it is often challenging to translate these results to full scale WRPs. This study uses a numerical modeling approach to investigate the influence of physical and chemical heterogeneities, structure, and scale on the release of acid rock drainage (ARD) through 2D reactive transport simulations. Specifically, the sensitivity of drainage quality to parameters including grain size distribution, sulfide mineral weathering rates, abundance and distribution of primary minerals, and pile structure as a function of construction methods are investigated. The geochemical model includes sulfide oxidation, pH buffering by calcite dissolution, and ferrihydrite and gypsum as secondary phases. Simulation results indicate that the implications of heterogeneity and construction method are scale-dependent; when grain size distribution trends observed in a pile's core are applied to the entirety of a pile, results between push- and end-dumping methods vary substantially—however, predicted drainage for different construction methods become more similar when features such as traffic surfaces, structural variation, and multiple benches are also considered. For all scales and construction methods investigated, simulated results demonstrate that pile heterogeneity and structure decrease peak mass loading rates 2 to 3-fold, but cause prolonged ARD release compared to the homogeneous case. These findings have implications for the economics of planning water treatment facilities for life of mine and closure operations.

scholarly journals Analysis of indices and operation improvement conditions of JSC “Ural Steel” blast furnace shop

2018 ◽  
pp. 46-54
Author(s):  
D. R. Ganin ◽  
V. G. Druzhkov ◽  
A. A. Panychev ◽  
A. Yu. Fuks
Keyword(s):  
Grain Size ◽  
Blast Furnace ◽  
Chemical Composition ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Iron Ore ◽  
Fine Fraction ◽  
Production Operation ◽  
Blast Furnaces ◽  
Furnace Technology

For elaborating of measures to improve the blast furnace technology, it is necessary to analyze production data related to blast furnaces operation. Estimation of technical level of blast furnace production in conditions of JSC “Ural Steel” was the aim of the study. Data on chemical composition of casted iron produced and burden materials quoted, as well as data on iron ore materials consumption, sinter grain-size distribution, pellets chemical composition and strength characteristics, coke mechanical strength and grain-size distribution. Results of analysis presented of production operation indices of Nos 1–4 blast furnaces within a five years period, the furnaces having net volumes 1007, 1033, 1513 and 2002 m3 correspondently. Periods of non-stable furnaces operation with long stops and repairs were excluded from the analyzed data. It was determined that iron and manganese oxide contents in the sinter are presented at lower level comparing with most of sintering plants of European Communities and Japan. Fine fraction less 5 mm content is considerably higher than the index for sinter, produced at other sintering plants of Russia, as well as of developed nations. Laboratory study and experimental-industrial tests at JSC “Ural Steel” confirm reasonability of the following mineral additives utilization in sintering process, delivered into the sintering burden by sludge: brown iron ore, bentonite clay, serpentinite-magnesites, that enables to increase suitable sinter yield, productivity of sintering machines, sinter impact strength. A necessity to optimize blast furnace slags chemical composition by relation SiO2/Al2O3 and CaO/MgO determined to improve scull formation conditions and elimination of coolers mass burning-through. To improve the technical and economic indices of JSC “Ural Steel blast furnaces operation some measures on the plant blast furnace technology modification proposed.

Downstream evolution of grain size in extremely mobile post-earthquake debris flows, China

2021 ◽  
Author(s):  
Erin L. Harvey ◽  
Tristram C. Hales ◽  
Daniel E. J. Hobley ◽  
Xuanmei Fan ◽  
Jie Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Debris Flow ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Debris Flows ◽  
Fine Fraction ◽  
Excess Pore Pressure ◽  
Extreme Rainfall Event ◽  
2008 Wenchuan Earthquake ◽  
Grain Sizes

&lt;p&gt;Large, catchment transitioning debris flows are an important mechanism for transporting sediment from hillslopes into higher order channels. Extremely large flows can exceed volumes of 10&lt;sup&gt;9&lt;/sup&gt; m&lt;sup&gt;3&lt;/sup&gt;, however even flows with volumes of&amp;#160; ~10&lt;sup&gt;3&lt;/sup&gt; m&lt;sup&gt;3&lt;/sup&gt; can lead to fatalities and extensive damage. Few processes transport a wider range of grain sizes than debris flows, which can transport grains from clays to 10 m boulders. While the structure of debris flows can often be inferred by their deposits, the range of grain sizes presents a challenge for their interpretation. Debris flow grain size distributions can be used to constrain debris flow runout due to their effect on excess pore pressure dissipation. Currently, there is limited data available for the entire grain size distribution of debris flow deposits in the field.&lt;/p&gt;&lt;p&gt;We constrained the entire grain size distribution for two extremely large (&gt;1 km in length) post-earthquake debris flows in Sichuan Province, China. These debris flows were triggered in August 2019 after an extreme rainfall event occurred close to the epicentre of the 2008 Wenchuan earthquake. We sampled the debris flows in November 2019 at intervals of 200 m and 500 m, respectively. At each site, we used a combination of field and laboratory sieving to obtain the coarse and fine fraction for both the surface and subsurface. We dug 1 m x 1 m x 0.5 m pits, excavating each layer at 10 cm depth increments. We sieved these increments into five size fractions in the field, including &lt; 1 cm. We sieved 1 kg of the &lt;1 cm fraction in the laboratory to estimate the distribution of the finest grains. The coarse surface fraction was then independently constrained using photogrammetry. Preliminary results for one debris flow show that the distribution of fine grains (~&lt;4 mm) is consistent both laterally and vertically across the runout. This suggests that the processes occurring vertically and laterally during deposition result in the consistent distribution of fines.&lt;/p&gt;

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