Bioreactor Process Optimization for Bioleaching of Fine-Grained Residues from Copper Smelting

2015 ◽  
Vol 1130 ◽  
pp. 321-324 ◽  
Author(s):  
Cindy Klink ◽  
Juliane Heim ◽  
Birgit Daus ◽  
Sebastian Eisen ◽  
Michael Schlömann ◽  
...  
Keyword(s):  
Metal Extraction ◽  
Copper Smelting ◽  
Small Scale ◽  
Toxic Heavy Metals ◽  
Fine Grained ◽  
Acidophilic Bacteria ◽  
Leaching Solution ◽  
Leaching Residue ◽  
Xrf Analyses ◽  
Bioreactor Process

Theisen sludge, a fine-grained by-product from copper smelting is a secondary resource for the winning of strategic elements by metal-oxidizing acidophilic bacteria. Screening for cultures, that grew in presence of the toxic heavy metals containing fly ash was successfully performed. Small scale experiments in shaking flasks with subsequent analysis of the pregnant leaching solution (PLS) revealed biological extraction of the major (zinc and copper) and minor metals (cobalt and rhenium). Results were confirmed by XRF analyses of the leaching residue. The bioleaching approach was up-scaled in stirred tank bioreactors under controlled conditions. Optimization of metal-extraction rates will be achieved by regulation of process-parameters, predominantly the redox-potential.

Small-scale plasticity of ultra-fine grained alloy and nanostructured nanocomposite: Ambient and elevated-temperature nanoindentation

2021 ◽  
Vol 807 ◽  
pp. 140873
Author(s):  
F. Khodabakhshi ◽  
A.P. Gerlich ◽  
D. Verma ◽  
M. Nosko ◽  
M. Haghshenas
Keyword(s):  
Elevated Temperature ◽  
Small Scale ◽  
Fine Grained

scholarly journals Changes in ground deformation prior to and following a large urban landslide in La Paz, Bolivia revealed by advanced InSAR

2018 ◽  
Author(s):  
Nicholas J. Roberts ◽  
Bernhard T. Rabus ◽  
John J. Clague ◽  
Reginald L. Hermanns ◽  
Marco-Antonio Guzmán ◽  
...  
Keyword(s):  
Ground Deformation ◽  
Ground Surface ◽  
Slope Instability ◽  
Small Scale ◽  
Spatial And Temporal Patterns ◽  
La Paz ◽  
Fine Grained ◽  
Measured Displacement ◽  
Optical Satellite Images ◽  
Displacement Patterns

Abstract. We characterize and compare creep preceding and following the 2011 Pampahasi landslide (∼ 40 Mm3 ± 50 %) in the city of La Paz, Bolivia, using spaceborne RADAR interferometry (InSAR) that combines displacement records from both distributed and point scatterers. The failure remobilised deposits of an ancient landslide in weakly cemented, predominantly fine-grained sediments and affected ∼ 1.5 km2 of suburban development. During the 30 months preceding failure, about half of the toe area was creeping at 3–8 cm/a and localized parts of the scarp area showed displacements of up to 14 cm/a. Changes in deformation in the 10 months following the landslide are contrary to the common assumption that stress released during a discrete failure increases stability. During that period, most of the landslide toe and areas near the headscarp accelerated, respectively, to 4–14 and 14 cm/a. The extent of deformation increased to cover most, or probably all, of the 2011 landslide as well as adjacent parts of the slope and plateau above. The InSAR-measured displacement patterns – supplemented by field observations and by optical satellite images – indicate that kinematically complex, steady-state creep along pre-existing sliding surfaces temporarily accelerated in response to heavy rainfall, after which the slope quickly achieved a slightly faster and expanded steadily creeping state. This case study demonstrates that high-quality ground-surface motion fields derived using spaceborne InSAR can help to characterize creep mechanisms, quantify spatial and temporal patterns of slope activity, and identify isolated small-scale instabilities. Characterizing slope instability before, during, and after the 2011 Pampahasi landslide is particularly important for understanding landslide hazard in La Paz, half of which is underlain by similar, large paleolandslides.

Optimization of a Leaching Tank for Hydrometallurgical Recovery of Metals

2009 ◽  
Author(s):  
M. C. L. G. Vilarinho ◽  
N. M. B. Gonc¸alves ◽  
J. C. F. Teixeira
Keyword(s):  
Laboratory Tests ◽  
Metal Extraction ◽  
Cfd Model ◽  
High Concentration ◽  
Metal Plating ◽  
Metals Recovery ◽  
High Metal ◽  
Leaching Solution ◽  
Wide Compositional Range ◽  
Overall Efficiency

The sludge wastes generated by the metal plating industries are classified as hazardous wastes because of their high concentration of heavy metals. Amongst the various routes for their treatment, the hydrometallurgical processes are highly attractive because they can be tailored to the wide compositional range of such wastes and assure its metals recovery and/or toxicity reduction. In these processes the leaching operation is paramount to the overall efficiency. In this, the mixing of the leaching solution with sludge has to be effective in order to obtain high levels of metal extraction and make the process attractive. Most of the available data refers to laboratory tests. This paper reports on the use of CFD model to optimize the operation of a pilot size leaching tank. The results regarding the velocity field were compared with experimental data and proved that such techniques can be effectively applied to improve the process. A leaching experiment, with the best configuration for the mixing, yielded a high metal extraction, suggesting that this technique can be successfully implemented for the treatment of such wastes.

scholarly journals Beyond Welfare Chauvinism and Deservingness. Rationales of Belonging as a Conceptual Framework for the Politics and Governance of Migrants’ Rights

2020 ◽  
pp. 1-23
Author(s):  
EMMA CARMEL ◽  
BOŻENA SOJKA
Keyword(s):  
Conceptual Framework ◽  
Social Exclusion ◽  
Social Protection ◽  
Small Scale ◽  
Fine Grained ◽  
Interpretive Analysis ◽  
Alternative Approach ◽  
Migrants Rights ◽  
The Uk

Abstract This article argues that the politics and governance of migrants’ rights needs to be reframed. In particular, the terms “welfare chauvinism”, and deservingness should be replaced. Using a qualitative transnational case study of policymakers in Poland and the UK, we develop an alternative approach. In fine-grained and small-scale interpretive analysis, we tease out four distinct “rationales of belonging” that mark out the terms and practices of social membership, as well as relative positions of privilege and subordination. These rationales of belonging are: temporal-territorial, ethno-cultural, labourist, and welfareist. Importantly, these rationales are knitted together by different framings of the transnational contexts, within which the politics and governance of migration and social protection are given meaning. The rationales of belonging do not exist in isolation, but, in each country, they qualify each other in ways that imply different politics and governance of migrants’ rights. Taken together, these rationales of belonging generate transnational projects of social exclusion, as well as justifications for migrant inclusion stratified by class, gender and ethnicity.

scholarly journals Changes in ground deformation prior to and following a large urban landslide in La Paz, Bolivia, revealed by advanced InSAR

2019 ◽  
Vol 19 (3) ◽  
pp. 679-696 ◽  
Author(s):  
Nicholas J. Roberts ◽  
Bernhard T. Rabus ◽  
John J. Clague ◽  
Reginald L. Hermanns ◽  
Marco-Antonio Guzmán ◽  
...  
Keyword(s):  
Ground Deformation ◽  
Ground Surface ◽  
Small Scale ◽  
Spatial And Temporal Patterns ◽  
La Paz ◽  
Fine Grained ◽  
Measured Displacement ◽  
Optical Satellite Images ◽  
Displacement Patterns ◽  
Spaceborne Radar

Abstract. We characterize and compare creep preceding and following the complex 2011 Pampahasi landslide (∼40 Mm3±50 %) in the city of La Paz, Bolivia, using spaceborne radar interferometry (InSAR) that combines displacement records from both distributed and point scatterers. The failure remobilized deposits of an ancient complex landslide in weakly cemented, predominantly fine-grained sediments and affected ∼1.5 km2 of suburban development. During the 30 months preceding failure, about half of the toe area was creeping at 3–8 cm a−1 and localized parts of the scarp area showed displacements of up to 14 cm a−1. Changes in deformation in the 10 months following the landslide demonstrate an increase in slope activity and indicate that stress redistribution resulting from the discrete failure decreased stability of parts of the slope. During that period, most of the landslide toe and areas near the head scarp accelerated, respectively, to 4–14 and 14 cm a−1. The extent of deformation increased to cover most, or probably all, of the 2011 landslide as well as adjacent parts of the slope and plateau above. The InSAR-measured displacement patterns, supplemented by field observations and optical satellite images, reveal complex slope activity; kinematically complex, steady-state creep along pre-existing sliding surfaces accelerated in response to heavy rainfall, after which slightly faster and expanded steady creeping was re-established. This case study demonstrates that high-quality ground-surface motion fields derived using spaceborne InSAR can help to characterize creep mechanisms, quantify spatial and temporal patterns of slope activity, and identify isolated small-scale instabilities; such details are especially useful where knowledge of landslide extent and activity is limited. Characterizing slope activity before, during, and after the 2011 Pampahasi landslide is particularly important for understanding landslide hazard in La Paz, half of which is underlain by similar large paleolandslides.

scholarly journals Experimental insights into consolidation rates during one-dimensional loading with special reference to excess pore water pressure

2020 ◽  
Vol 15 (12) ◽  
pp. 3571-3591
Author(s):  
Bartłomiej Szczepan Olek
Keyword(s):  
Pore Water ◽  
Large Scale ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Small Scale ◽  
Coefficient Of Consolidation ◽  
Consolidation Process ◽  
Factors Affecting ◽  
Fine Grained ◽  
Fine Grained Soil

AbstractConsolidation rate has significant influence on the settlement of structures founded on soft fine-grained soil. This paper presents the results of a series of small-scale and large-scale Rowe cell consolidation tests with pore water pressure measurements to investigate the factors affecting the consolidation process. Permeability and creep/resistance structure factors were considered as the governing factors. Intact and reconstituted marine clay from the Polish Carpathian Foredeep basin as well as clay–sand mixtures was examined in the present study. The fundamental relationship correlating consolidation degrees based on compression and pore water pressure was assessed to indicate the nonlinear soil behaviour. It was observed that the instantaneous consolidation parameters vary as the process progresses. The instantaneous coefficient of consolidation first drastically increases or decreases with increase in the degree of consolidation and stabilises in the middle stage of the consolidation; it then decreases significantly due to viscoplastic effects occurring in the soil structure. Based on the characteristics of the relationship between coefficient of consolidation and degree of dissipation at the base, the consolidation range that complies with theoretical assumptions was established. Furthermore, the influence of coarser fraction in clay–sand mixtures in controlling the consolidation rates is discussed.

scholarly journals Laboratory development of a vertically oriented penetrometer for shallow seabed characterization

2016 ◽  
Vol 53 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Fauzan Sahdi ◽  
David J. White ◽  
Christophe Gaudin ◽  
Mark F. Randolph ◽  
Noel Boylan
Keyword(s):  
Soil Surface ◽  
Site Investigation ◽  
Soil Strength ◽  
Small Scale ◽  
Soil Parameters ◽  
Embedment Depth ◽  
Fine Grained ◽  
Centrifuge Models ◽  
Measured Resistance ◽  
And Performance

Current site investigation practice for offshore pipeline design relies on soil parameters gathered from boreholes or in situ test soundings to depths of 1–2 m below the mudline. At these depths, the fine-grained seabed is very soft and possesses low undrained strength, which can be difficult to measure. This paper describes a centrifuge test programme undertaken to evaluate the feasibility and performance of a novel penetrometer designed to assess the shallow strength of soft seabed over continuous horizontal profiles. This device is termed the vertically oriented penetrometer (VOP). Tests were performed on a normally consolidated kaolin sample, with the VOP translated horizontally at velocities ranging from 1 to 30 mm/s, after embedding the VOP at 30 and 45 mm depths. All tests involved many cycles of VOP forward and backward movement to assess its potential to derive the ratio of intact to fully remoulded strength. Strength determination is achieved by dragging the VOP at a specified embedment depth along the soil surface, and deriving the soil strength from the measured resistance as if the VOP were a laterally loaded pile. The VOP is shown to yield comparable strength measurements to that of a T-bar penetrometer. The VOP is a potentially valuable addition to the range of tools used to characterize soil strength, both in small-scale centrifuge models and, following practical development, potentially also in the field.

scholarly journals Microstructural Investigations on Plasticity of Lime-Treated Soils

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 386
Author(s):  
Enza Vitale ◽  
Dimitri Deneele ◽  
Giacomo Russo
Keyword(s):  
Liquid Limit ◽  
Small Scale ◽  
Plastic Behavior ◽  
Short Term ◽  
Clay Particles ◽  
Fine Grained ◽  
Surface Charge Distribution ◽  
Plastic Changes ◽  
Interparticle Repulsion

The surface charge distribution of clay particles governs the interparticle forces and their arrangement in clay-water systems. The plasticity properties are the consequences of the interaction at the microscopic scale, even if they are traditionally linked to the mechanical properties of fine-grained soils. In the paper, the plasticity modifications induced by the addition of lime were experimentally investigated for two different clays (namely kaolinite and bentonite) in order to gain microstructural insights of the mechanisms affecting their plastic behavior as a function of the lime content and curing time. Zeta potential and dynamic light scattering measurements, as well as thermogravimetric analyses, highlighted the mechanisms responsible for the plastic changes at a small scale. The increase of the interparticle attraction forces due to the addition of lime increased the liquid and plastic limits of kaolinite in the short term, without significant changes in the long term due to the low reactivity of the clay in terms of pozzolanic reactions. The addition of lime to bentonite resulted in a decrease of interparticle repulsion double layer interactions. Rearrangement of the clay particles determined a reduction of the liquid limit and an increase of the plastic limit of the treated clays in the very short term. Precipitation of the bonding compounds due to pozzolanic reactions increased both the liquid and plastic limits over the time.

Experimental Study on Sulfuric Acid Leaching Behavior of Chromite with Different Temperature

2011 ◽  
Vol 361-363 ◽  
pp. 628-631 ◽  
Author(s):  
Cheng Jun Liu ◽  
Jie Qi ◽  
Mao Fa Jiang
Keyword(s):  
Sulfuric Acid ◽  
Acid Leaching ◽  
Raw Material ◽  
Leaching Rate ◽  
Sulfuric Acid Leaching ◽  
Leaching Process ◽  
Pollution Problem ◽  
Environmental Pollution Problem ◽  
Leaching Solution ◽  
Leaching Residue

Utilizing Pakistan chromite as raw material, the rapid leaching of chromium and iron could be realized by the sulfuric acid leaching process on the condition of atmospheric pressure and the addition of oxidant A. And the leaching rate of chromium and iron would be 98.5% and 71.9%, respectively. The sulfuric acid leaching processes with different temperature were systematically studied by chemical analysis and phase analysis. The results showed that, with the increase of reaction temperature, the leaching rate of chromium would increase gradually, but the leaching rate of iron increased at first and then decreases and reached its maximum at 140°C. When the temperature > 160°C, the phases of the leaching residue were magnesium iron silicate and a few of silica, no chromohercynite, chrompicotite and magnesioferrite existed in the chromite. The leaching solution of sulfuric acid leaching process could be used for preparing the basic chrome sulfate, and there is no Cr6+ in the leaching residue and solution. The results would provide theoretical guidance for solving environmental pollution problem of Cr6+ in traditional chromate production process.

Determination of the Residual Stress Field around Scratches Using Synchrotron X-Rays and Nanoindentation

2010 ◽  
Vol 652 ◽  
pp. 25-30
Author(s):  
M.K. Khan ◽  
Michael E. Fitzpatrick ◽  
L.E. Edwards ◽  
S.V. Hainsworth
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Small Scale ◽  
X Rays ◽  
X Ray Diffraction ◽  
Residual Stress Field ◽  
Fine Grained ◽  
Load Displacement

The residual strain field around the scratches of 125µm depth and 5µm root radius have been measured from the Synchrotron X-ray diffraction. Scratches were produced using different tools in fine-grained aluminium alloy AA 5091. Residual stresses up to +1700 micro-strains were measured at the scratch tip for one tool but remained up to only +1000 micro-strains for the other tool scratch. The load-displacement curves obtained from nanoindentation were used to determine the residual stresses around the scratches. It was found that the load-displacement curves are sensitive to any local residual stress field present and behave according to the type of residual stresses. This combination of nanoindentation and synchrotron X-rays has been proved highly effective for the study of small-scale residual stresses around the features such as scratches.

Sign in / Sign up

Export Citation Format

Share Document