scholarly journals Counter-Current Leaching of Low-Grade Laterites with Hydrochloric Acid and Proposed Purification Options of Pregnant Solution

Minerals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 599 ◽  
Author(s):  
Christiana Mystrioti ◽  
Nymphodora Papassiopi ◽  
Anthimos Xenidis ◽  
Konstantinos Komnitsas
Keyword(s):  
Hydrochloric Acid ◽  
Current Mode ◽  
Leach Solution ◽  
Low Grade ◽  
Mode Of Operation ◽  
Oxidative Precipitation ◽  
Alkaline Earths ◽  
Low Levels ◽  
Counter Current ◽  
Mn Oxides

A hydrochloric acid hydrometallurgical process was evaluated for Ni and Co extraction from a low-grade saprolitic laterite. The main characteristics of the process were (i) the application of a counter-current mode of operation as the main leaching step (CCL), and (ii) the treatment of pregnant leach solution (PLS) with a series of simple precipitation steps. It was found that, during CCL, co-dissolution of Fe was maintained at very low levels, i.e., about 0.6%, which improved the effectiveness of the subsequent PLS purification step. The treatment of PLS involved an initial precipitation step for the removal of trivalent metals, Fe, Al, and Cr, using Mg(OH)2. The process steps that followed aimed at separating Ni and Co from Mn and the alkaline earths Mg and Ca, by a combination of repetitive oxidative precipitation and dissolution steps. Magnesium and calcium remained in the aqueous phase, Mn was removed as a solid residue of Mn(III)–Mn(IV) oxides, while Ni and Co were recovered as a separate aqueous stream. It was found that the overall Ni and Co recoveries were 40% and 38%, respectively. About 45% of Ni and 37% of Co remained in the leach residue, while 15% Ni and 20% Co were lost in the Mn oxides.

Empirical Model to Estimate Mn2+ Precipitation Rate from a Leaching Solution Using SO2/O2 as Oxidizing Agent

2012 ◽  
Vol 1380 ◽  
Author(s):  
S. Bello-Teodoro ◽  
R. Pérez-Garibay
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Reaction Rates ◽  
Precipitation Process ◽  
Low Grade ◽  
Gas Flow Rate ◽  
Oxidative Precipitation ◽  
Leaching Solution ◽  
Good Concordance ◽  
Main Influence

ABSTRACTA method, based in leaching with SO2, to process low grade pyrolusite minerals has shown good results at laboratory scale. After the separation of the solid impurities, the dissolved manganese is subsequently precipitated using the SO2/O2 gas mixture as oxidising agent. In this research it was obtained a mathematical model to estimate the oxidative precipitation process, as a function of temperature, pH and SO2 gas flow rate. It was found that pH and temperature have the main influence in the reaction rate. An optimal SO2 concentration in the mixture must be used to avoid generation of reductive conditions. It was observed a most efficient reaction with a low gas flow rate injection. The predicted reaction rates presents a good concordance with the experimental results (R2=0.97), showing a worthy potential for practical uses.

Uranium Bioleaching from Low Grade Ore

2020 ◽  
Vol 989 ◽  
pp. 559-563
Author(s):  
Ashimkhan T. Kanayev ◽  
Khussain Valiyev ◽  
Aleksandr Bulaev
Keyword(s):  
Sulfuric Acid ◽  
Acid Mine Drainage ◽  
Mine Drainage ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Leach Solution ◽  
Low Grade ◽  
Bacterial Cells ◽  
Acid Mine

The goal of the present work was to perform bioleaching of uranium from low grade ore from Vostok deposit (Republic of Kazakhstan), which was previously subjected to long-term acid leaching. The ore initially contained from 0.15 to 0.20% of uranium in the form of uraninite, but ore samples used in the study contained about 0.05% of uranium, as it was exhausted during acid leaching, and uranium was partially leached. Representative samples of ore were processed in 1 m columns, leach solutions containing 5, 10, 20 g/L of sulfuric acid and bacterial cells (about 104) were percolated through the ore. Leaching was performed at ambient temperature for 70 days. In one of the percolators, the leaching was performed with leaching solution containing 10 g/L of H2SO4, cells of A. ferrooxidans, and 0.5 g/L of formaldehyde. Leaching with the solution containing 5, 10, and 20 g/L of sulfuric acid made it possible to extract 50, 53, and 58% of uranium. Addition of formaldehyde in leach solution led to the decrease in uranium extraction extent down to 37%. Thus, the results of the present work demonstrated that uranium ore exhausted during long-term acid leaching may be successfully subjected to bioleaching, that allows extracting residual quantities of uranium. Leaching rate of uranium from exhausted ore depended on both sulfuric acid concentration and microbial activity of bacteria isolated from acid mine drainage, formed on uranium deposit. In the same time, acid mine drainage may be used as a source of inoculate, to start bioleaching process.

Mineralogical and textural evolution of the economic manganese mineralisation in western Rhodope massif, N. Greece

1991 ◽  
Vol 55 (380) ◽  
pp. 423-434 ◽  
Author(s):  
M. K. Nimfopoulos ◽  
R. A. D. Pattrick
Keyword(s):  
Surface Water ◽  
Water Table ◽  
Fault Zones ◽  
Hydrothermal Fluids ◽  
Mineral Paragenesis ◽  
Textural Evolution ◽  
Mn Oxide ◽  
Alkaline Earths ◽  
Mn Oxides ◽  
Hydrothermal Veins

AbstractThe western Rhodope massif contains a significant number of ‘battery grade’ Mn-oxide deposits which are best developed in the area near Kato Nevrokopi, Drama district, N. Greece. Economic Mn-oxide ore concentrations are confined to fault zones and related karsts in marbles. The mineralisation has formed by weathering of hydrothermal veins that were genetically related to Oligocene magmatism.At Kato Nevrokopi, progressive and continuous weathering of primary, hydrothermal veins of rhodochrosite, mixed sulphide, quartz and ‘black calcite’ (calcite and todorokite) has resulted in the formation of the assemblage MnO-gel-(amorphous Mn-oxide)-todorokite-azurite-goethite-cerussite in the veins and the assemblage MnO-gel-nsutite-chalcophanite-birnessite-cryptomelane-pyrolusite and malachite and amorphous Fe-oxides in karstic cavities.The fs2 and fO2 of the hydrothermal fluids increased with time. The breakdown of the hypogene Mn-carbonate was aided by the production of an acidic fluid due to the oxidation of sulphides. Precipitation of the supergene ores was caused by neutralisation of the fluids due to reaction with the host marble and to mixing of relatively reduced fluids with oxygenated surface water in a fluctuation water table regime. Zinc was also mobile during weathering and became concentrated in the intermediate Mn-oxides, effectively stabilising their structures. The mineral paragenesis records the progressive oxidation of the ore and the appearance of less hydrated Mn-oxides, low in alkalis and alkaline earths.

scholarly journals The kinetic study of limonitic low grade nickel ore leaching using hydrochloric acid

2019 ◽  
Vol 478 ◽  
pp. 012009
Author(s):  
H S E A Gustiana ◽  
I M Bendiyasa ◽  
Agus Prasetya ◽  
F R Mufakhir ◽  
W Astuti ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Kinetic Study ◽  
Low Grade

scholarly journals Builders' Perceptions of Lowest Cost Procurement and Its Impact on Quality

2012 ◽  
Vol 9 (1) ◽  
pp. 1-8
Author(s):  
Mary Hardie ◽  
Swapan Saha
Keyword(s):  
Selection Process ◽  
Current Mode ◽  
Adverse Impact ◽  
Contractor Selection ◽  
Project Outcomes ◽  
Diffi Cult ◽  
Industry Performance ◽  
Mode Of Operation ◽  
Quality Of Outcome

to the degree to which it meets the customer’s needs andexpectations. Dissatisfaction with the quality of building projectshas been widely reported in recent times. There are indicationsthat there may be some relationship between the procurementmethod used and customer satisfaction with the delivered product.In particular, traditional competitive bid contracting may havean adverse impact on quality in some circumstances. To shedsome light on reported industry attitudes, a survey of constructionprofessionals in the Sydney metropolitan area was undertaken.The respondents demonstrate mixed views on the effectivenessof the competitive tender system on quality project outcomes. Tosome extent contractors’ attitudes may be determined by theirpreferred current mode of operation. However, some supportis expressed for the contention that quality of outcome can bereduced by an overly cost driven contractor selection process. Inparticular, when economic pressures cause bidders to reduce thetime allocated for the tender process, an inaccurate and unreliablebid may win. This makes it very diffi cult for the reliable contractorto remain profi table. A move to value-based rather than cost-basedprocurement may assist industry performance and customersatisfaction.

Hot test of partitioning strontium from high-level liquid waste (HLLW) by dicyclohexano-18crown-6 (DCH18C6)

2001 ◽  
Vol 89 (3) ◽  
Author(s):  
W. Jianchen ◽  
S. Chongli
Keyword(s):  
Crown Ether ◽  
Liquid Waste ◽  
Current Mode ◽  
Feed Solution ◽  
High Level Liquid Waste ◽  
Trpo Process ◽  
Centrifugal Contactor ◽  
High Level ◽  
Counter Current ◽  
Hot Test

The crown ether strontium extraction(CESE) process for partitioning strontium from HLLW was studied. A hot test was carried out in a counter current mode with genuine HLLW by using a miniature centrifugal contactor set. 0.1 mol/L DCH18C6 in 1-octanol was used as extractant. The feed solution was the HLLW raffinate of TRPO process after removing TRU elements. Acidity of the feed was 1.45 mol/L HNO

Low Levels of Thrombin Activatable Fibrinolysis Inhibitor (TAFI) in Patients with Chronic Liver Disease

2001 ◽  
Vol 85 (04) ◽  
pp. 667-670 ◽  
Author(s):  
Magdalene George ◽  
Jawed Fareed ◽  
David Van Thiel
Keyword(s):  
Liver Disease ◽  
Chronic Liver Disease ◽  
Degradation Products ◽  
Chronic Liver ◽  
Low Grade ◽  
Thrombin Activatable Fibrinolysis Inhibitor ◽  
Disseminated Intravascular Coagulopathy ◽  
Fibrinolysis Inhibitor ◽  
Intravascular Coagulopathy ◽  
Low Levels

SummaryThrombin Activatable Fibrinolysis Inhibitor (TAFI) is a 60 κD glycoprotein present in plasma that regulates fibrinolysis by limiting the amount of fibrin available for fibrinolysis by tissue plasminogen activator (t-PA). Chronic liver disease is well-known to be associated with a low-grade fibrinolytic syndrome that under the appropriate stimulus proceeds to an overt disseminated intravascular coagulopathy (DIC) with demonstrable bleeding. In the present study, TAFI activity was measured in the plasma of 74 patients with advanced liver disease, and the levels of TAFI were related to those of other important coagulation and fibrinolytic factors. TAFI levels were very low and essentially undetectable in the plasma of patients with advanced hepatocellular liver disease. No relationship with the degradation products of fibrin was evident.

A process for beneficiation of low-grade manganese ore and synchronous preparation of calcium sulfate whiskers during hydrochloric acid regeneration

2021 ◽  
Vol 199 ◽  
pp. 105533
Author(s):  
Mengen Lei ◽  
Baozhong Ma ◽  
Dongya Lv ◽  
Chengyan Wang ◽  
Edouard Asselin ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Calcium Sulfate ◽  
Low Grade ◽  
Manganese Ore ◽  
Calcium Sulfate Whiskers

scholarly journals Sustainable Hydrometallurgical Recovery of Valuable Elements from Spent Nickel–Metal Hydride HEV Batteries

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1062 ◽  
Author(s):  
Kivanc Korkmaz ◽  
Mahmood Alemrajabi ◽  
Åke Rasmuson ◽  
Kerstin Forsberg
Keyword(s):  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Hybrid Electric Vehicle ◽  
Active Material ◽  
Sulfuric Acid Concentration ◽  
Dissolution Kinetics ◽  
Leach Solution ◽  
Nickel Metal ◽  
Acid Leach ◽  
Kinetics Of

In the present study, the recovery of valuable metals from a Panasonic Prismatic Module 6.5 Ah NiMH 7.2 V plastic casing hybrid electric vehicle (HEV) battery has been investigated, processing the anode and cathode electrodes separately. The study focuses on the recovery of the most valuable compounds, i.e., nickel, cobalt and rare earth elements (REE). Most of the REE (La, Ce, Nd, Pr and Y) were found in the anode active material (33% by mass), whereas only a small amount of Y was found in the cathode material. The electrodes were leached in sulfuric acid and in hydrochloric acid, respectively, under different conditions. The results indicated that the dissolution kinetics of nickel could be slow as a result of slow dissolution kinetics of nickel oxide. At leaching in sulfuric acid, light rare earths were found to reprecipitate increasingly with increasing temperature and sulfuric acid concentration. Following the leaching, the separation of REE from the sulfuric acid leach liquor by precipitation as NaREE (SO4)2·H2O and from the hydrochloric acid leach solution as REE2(C2O4)3·xH2O were investigated. By adding sodium ions, the REE could be precipitated as NaREE (SO4)2·H2O with little loss of Co and Ni. By using a stoichiometric oxalic acid excess of 300%, the REE could be precipitated as oxalates while avoiding nickel and cobalt co-precipitation. By using nanofiltration it was possible to recover hydrochloric acid after leaching the anode material.

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