Recovery of copper sulphides mineral grains at coarse rock fragments size

2014 ◽  
Vol 64 ◽  
pp. 131-138 ◽  
Author(s):  
Nenad Djordjevic
Keyword(s):  
Rock Fragments ◽  
Copper Sulphides

Quantifying organic carbon stocks using a stereological profile imaging method to account for rock fragments in stony soils

Geoderma ◽  
2021 ◽  
Vol 385 ◽  
pp. 114837
Author(s):  
Zhuo-Dong Jiang ◽  
Qiu-Bing Wang ◽  
Kristofor R. Brye ◽  
Kabindra Adhikari ◽  
Fu-Jun Sun ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Stocks ◽  
Imaging Method ◽  
Rock Fragments

scholarly journals Stress level effect on mobility of dry granular flows of angular rock fragments

Landslides ◽  
2021 ◽  
Author(s):  
B. Cagnoli
Keyword(s):  
Stress Level ◽  
Granular Flow ◽  
High Stress ◽  
Granular Flows ◽  
Flow Dynamics ◽  
Small Scale ◽  
Flow Volume ◽  
Rock Fragments ◽  
Rock Avalanches ◽  
Flow Mobility

AbstractGranular flows of angular rock fragments such as rock avalanches and dense pyroclastic flows are simulated numerically by means of the discrete element method. Since large-scale flows generate stresses that are larger than those generated by small-scale flows, the purpose of these simulations is to understand the effect that the stress level has on flow mobility. The results show that granular flows that slide en mass have a flow mobility that is not influenced by the stress level. On the contrary, the stress level governs flow mobility when granular flow dynamics is affected by clast agitation and collisions. This second case occurs on a relatively rougher subsurface where an increase of the stress level causes an increase of flow mobility. The results show also that as the stress level increases, the effect that an increase of flow volume has on flow mobility switches sign from causing a decrease of mobility at low stress level to causing an increase of mobility at high stress level. This latter volume effect corresponds to the famous Heim’s mobility increase with the increase of the volume of large rock avalanches detected so far only in the field and for this reason considered inexplicable without resorting to extraordinary mechanisms. Granular flow dynamics is described in terms of dimensionless scaling parameters in three different granular flow regimes. This paper illustrates for each regime the functional relationship of flow mobility with stress level, flow volume, grain size, channel width, and basal friction.

Late Wisconsinan glacial stratigraphy and history of southeastern Manitoba

1980 ◽  
Vol 17 (1) ◽  
pp. 19-35 ◽  
Author(s):  
James T. Teller ◽  
Mark M. Fenton
Keyword(s):  
Carbonate Rocks ◽  
Lacustrine Sediment ◽  
Precambrian Rock ◽  
Lake Agassiz ◽  
Rock Fragments ◽  
Lithostratigraphic Units ◽  
Stratigraphic Position ◽  
History Of ◽  
International Boundary ◽  
Late Wisconsinan

The history of Late Wisconsinan glaciation in southwestern Manitoba has been established by identifying and correlating ice-laid lithostratigraphic units in the subsurface. Five Late Wisconsinan tills are defined on the basis of their texture, mineralogic composition, and stratigraphic position. These new formations are, from youngest to oldest, Marchand, Whitemouth Lake, Roseau, Senkiw, and Whiteshell Formations.Late Wisconsinan ice first invaded southeastern Manitoba 22 000 to 24 000 years ago. This Laurentide glacier advanced from the northeast across the Precambrian Shield and deposited the sandy Whiteshell and Senkiw tills, which contain abundant Precambrian rock fragments and minerals and few Paleozoic carbonate grains. Shortly after this, Keewatin ice advanced from the northwest over Paleozoic carbonate rocks, depositing the loamy carbonate-rich Roseau Formation throughout most of the area. This ice remained over southeastern Manitoba until after 13 500 years ago, when it rapidly retreated northward with Lake Agassiz on its heels. Two brief glacial readvances occurred. The first overrode Lake Agassiz lacustrine sediment as far south as central North Dakota shortly after about 13 000 years ago. The clayey Whitemouth Lake till was deposited in southern Manitoba at this time. After a rapid retreat, the ice briefly pushed southward over southeastern Manitoba about 12 000 years ago to just south of the International Boundary. The sandy carbonate-rich Marchand Formation was deposited at this time as the ice overrode its own sandy outwash. By 11 000 years ago, ice had disappeared from southeastern Manitoba.

scholarly journals Revegetation in abandoned quarries with landfill stabilized waste and gravels: water dynamics and plant growth – a case study

2017 ◽  
Author(s):  
Cheng-liang Zhang ◽  
Jing-jing Feng ◽  
Li-ming Rong ◽  
Ting-ning Zhao
Keyword(s):  
Plant Growth ◽  
Water Content ◽  
Robinia Pseudoacacia ◽  
Water Dynamics ◽  
Leaf Water Content ◽  
Rock Fragments ◽  
Platycladus Orientalis ◽  
Concrete Production ◽  
Uppermost Layer ◽  
Pavement Construction

Abstract. Large amounts of quarry wastes are produced during quarrying. Though quarry wastes are commonly used in pavement construction and concrete production, in-situ utilization during ecological restoration of abandoned quarries has its advantage of simplicity. In this paper, rock fragments of 2 ~ 3 cm in size were mixed with landfill stabilized waste (LSW) in different proportions (LSW: gravel, RL), which was called LGM. The water content, runoff and plant growth under natural precipitation were monitored for two years using a runoff plot experiment. LGM with a low fraction of LSW was compacted in different degrees to achieve an appropriate porosity; water dynamic and plant growth of compacted LGM were studied in a field experiment. The results showed that, (1) LGM can be used during restoration in abandoned quarries as growing material for plants. (2) RL had a significant effect on infiltration and water holding capacity of LGM, and thus influenced retention of precipitation, water condition and plant growth. LGM with RL ranging from 8 : 1 to 3 : 7 was suitable for plant growth, but the target species grew best when RL was intermediate. (3) Compaction significantly enhanced water content of LGM with a low RL of 2 : 8, but leaf water content of plants was lower or unchanged in the more compacted plots. Moderate compaction was beneficial to the survival and growth of Robinia pseudoacacia. Platycladus orientalis and Medicago sativa were not significantly affected by compaction, and they grew better under high degree of compaction which was disadvantageous for the uppermost layer of vegetation.

Mechanochemical transformations and reactivity in copper sulphides

2003 ◽  
Vol 64 (8) ◽  
pp. 1413-1417 ◽  
Author(s):  
P Baláž ◽  
L Takacs ◽  
E Boldižárová ◽  
E Godočı́ková
Keyword(s):  
Copper Sulphides

Evidence for pyroclastic emplacement of the Crowsnest Formation, Alberta

1996 ◽  
Vol 33 (5) ◽  
pp. 715-728 ◽  
Author(s):  
R.N. Adair ◽  
R.A. Burwash
Keyword(s):  
Elevated Temperatures ◽  
Pyroclastic Flows ◽  
Coarse Grained ◽  
Rock Fragment ◽  
Fine Grained ◽  
Rock Fragments ◽  
Explosive Phase ◽  
Graded Structures ◽  
Textural Evidence ◽  
Charred Wood

The middle Cretaceous Crowsnest Formation west of Coleman, Alberta, is composed of bedded alkaline volcanic deposits containing heterolithic volcanic rock fragments and crystal clasts. Comparison with modern examples of subaerial pyroclastic rocks suggests that pyroclastic flows, surges, fallout of material from vertical eruption columns, and minor mud flows emplaced the deposits. Textural evidence in the form of plastically deformed volcanic fragments, chilled deposit margins, baked rock fragment margins, recrystallization, and the presence of charred wood and charred wood molds indicate emplacement at elevated temperature. Massive deposits containing a fine-grained basal zone are interpreted as the product of pyroclastic flows, whereas deposits characterized by a block-rich base overlain by a thin layer of block-depleted stratified material are interpreted as the product of density-stratified surges. Deposits exhibiting pronounced stratification were emplaced by ash-cloud surges. Thickly bedded breccias exhibiting rheomorphic textures were emplaced as vent-proximal pyroclastic flows. Deposits characterized by parallel beds and graded structures are interpreted as fallout tephra deposits, and deposition by lahars is indicated by coarse-grained beds that lack evidence for emplacement at elevated temperatures. The eruptions of the Crowsnest Formation were cyclical. An initial explosive phase generated deposits by pyroclastic flows, surges, fallout, and lahars. As an eruption progressed, it evolved into a poorly gas-charged effusive stage that emplaced coarsely porphyritic domes, plugs, spines, and vent-proximal lava flows. Subsequent eruptions destroyed the effusive vent facies deposits and produced abundant heterolithic clasts typical of the formation.

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