scholarly journals Leaching of Ca-Rich Slags Produced from Reductive Smelting of Bauxite Residue with Na2CO3 Solutions for Alumina Extraction: Lab and Pilot Scale Experiments

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 896
Author(s):  
Michail Vafeias ◽  
Amalia Bempelou ◽  
Eirini Georgala ◽  
Panagiotis Davris ◽  
Efthymios Balomenos ◽  
...  
Keyword(s):  
Calcium Aluminate ◽  
Bauxite Residue ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Raw Material ◽  
Fe Content ◽  
Alumina Industry ◽  
Reuse Options ◽  
The One ◽  
Two Stages

Sustainable utilization of Bauxite Residue (BR) is currently one of the greatest challenges being tackled by the alumina industry, due to its high production rates and limited reuse options. The present work is concerned with the use of BR as a candidate metallurgical raw material for iron (Fe) production and aluminum (Al) extraction. In more detail, at first, BR undergoes reductive smelting to extract its Fe content and produce a slag of mainly calcium aluminate composition. In a second step, Al contained in the calcium aluminate phases is extracted hydrometallurgically by leaching with a Na2CO3 aqueous solution. The focus of the current study is the optimization of this leaching process, and it was performed in two stages. The first was a laboratory scale investigation on the main parameters affecting the extraction rate of Al. The second stage was performed in pilot scale and incorporated observations and suggestions based on the laboratory scale investigation. Laboratory work showed that more than 50% of aluminum could be easily extracted in less than 1 h, in 5% S/L, at 70 °C and with an 20% excess of Na2CO3. Pilot scale work, by successfully applying the suggestions derived from laboratory scale work, achieved an average Al extraction of 68% from a 10% S/L pulp, with a slag of optimized composition in relation to the one used in the laboratory scale.

scholarly journals A study to set-up a technological process for purification of Zinc scraps by using liquation method

2021 ◽  
Vol 8 (1) ◽  
pp. 36-43
Author(s):  
Ngoc Vuong Tran ◽  
Manh Hung Luong ◽  
Dinh Dang Nguyen
Keyword(s):  
Zinc Oxide ◽  
Raw Materials ◽  
Time Factors ◽  
Pilot Scale ◽  
Raw Material ◽  
Optimal Time ◽  
Fe Content ◽  
Technology Process ◽  
Zn Content ◽  
Set Up

Zinc scrap is a source of raw material for zinc oxide production. However, to qualify the requirement of raw material for zinc oxide (99.5%) production, refining this source is needed. Many methods are considered such as rectification, chemical method, etc., but difficult to apply on an industrial scale. This workfocused on the investigation of the influence of temperature and time factors for asessing the possibility of applying liquation method for the purification of impurities from scrap zinc.The experiment results show that the optimum temperature of liquation to remove Pb,Fe from zinc scrap is in the range of 440-450°C, the optimal time of the process is 8h for the pot with 8cm in height and 6cm in diameter (the quantity of raw zinc sample is about 2kg / batch), then we can obtain about 80% of zinc metal with an average Zn content of about 97, 0%, both Pb and Fe content decreased to a range from 0.35 to 0.4%, and 1.0 to 1.1%, respectively, which meet the requirement of raw materials for the production of high quanlity ZnO ( 99,5 %). Based on the parameters obtained on lab-scale, a trial on pilot scale of 250 kg / batch was conducted, The result confirms that the quality of the products meets the requirement of raw materials for production of high quality ZnO (99.5%) and a technology process for refining zinc scrap by the liquation was proposed.

Low-temperature Conversion of Fe-rich Sludge to KFeS2 Whisker: a New Flocculant Synthesis From Laboratory Scale to Pilot Scale

2021 ◽  
Author(s):  
Dongxu Liang ◽  
Yu Chen ◽  
Suiyi Zhu ◽  
Yidi Gao ◽  
Tong Sun ◽  
...  
Keyword(s):  
Low Temperature ◽  
Cold Rolling ◽  
Freeze Drying ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Raw Material ◽  
Electroplating Wastewater ◽  
One Dimensional ◽  
Electroplating Effluent ◽  
Pure Grade

Abstract KFeS2 is a one-dimensional material and commonly used raw material for synthesising AgFeS2 and CuFeS2. With the solvothermal method, KFeS2 cluster could be synthesised at 190 °C with chemically pure grade Fe salt as Fe source. Herein, a KFeS2 whisker was formed in mass production at a low temperature, with waste cold-rolling sludge as Fe source, and exhibited good performance in the removal of Zn/Ni from real electroplating effluent. At laboratory scale, results showed that KFeS2 was not generated after heating at 50 °C for 24 h; however, after heating at 80 °C for 10 h, KFeS2 whisker (diameter and length of 0.2 and 0.5–1 mm, respectively) was produced, which grew radially to 1–4 mm after 24 h. This method was applied at pilot scale, where a similar KFeS2 whisker was also produced with waste cold-rolling sludge as Fe source. At pilot scale, a residual brownish supernatant was observed after the reaction and then completely recycled in the next round for KFeS2 synthesis. After recycling five times, the produced KFeS2 whisker did not change. For KFeS2 drying, freeze-drying and vacuum-drying were applicable, whilst air-drying was not profitable. The prepared KFeS2 was spontaneously hydrolysed in electroplating wastewater to generate Fe/S-bearing oxyhydroxide colloid for Zn/Ni removal. By adding 1 g of KFeS2, the residual levels of Zn/Ni were 0.22 and 0.02 mg/L, met the discharge standard of electroplating wastewater. Undried KFeS2 showed similar efficiencies of Zn/Ni removal to dried KFeS2, whose efficiencies were apparently higher than those with Na2S·9H2O, polymeric ferric sulfuric, sodium diethyldithiocarbamatre and lime. With the method, KFeS2 whisker was produced at pilot scale without generating any secondary waste and exhibited good performance in the treatment of electroplating wastewater.

scholarly journals Electrolytic iron production from alkaline bauxite residue slurries at low temperatures

2020 ◽  
Author(s):  
Sevasti Koutsoupa ◽  
Stavroula Koutalidi ◽  
Evangelos Bourbos ◽  
Efthymios Balomenos ◽  
Dimitrios Panias
Keyword(s):  
Iron Oxides ◽  
Bauxite Residue ◽  
Normal Pressure ◽  
Raw Material ◽  
Great Promise ◽  
Small Scale ◽  
Electrolysis Cell ◽  
Iron Production ◽  
Faradaic Efficiency ◽  
Alumina Industry

The primary iron metallurgy is characterized by significant direct CO2 emissions, due to the carbothermic reduction of the iron ore. This paper deals with the electrification of primary iron production by developing a new and innovative process for the carbon-free production of metallic iron from Bauxite Residue (BR) which is a by-product of the alumina industry. It is based on the electroreduction of iron oxides from BR suspensions in concentrated sodium hydroxide solutions, at low temperature and normal pressure. The iron oxide source, used in the present study is bauxite residue provided by Mytilineos S.A., Metallurgy Business Unit-Aluminium of Greece. The research study is a preliminary screening of BR as a potential raw material for iron production by performing experiments in a small-scale electrolysis cell. The first results presented here, show that iron can be produced by the reduction of iron oxides in the bauxite residue with high Faradaic efficiency (>70%). Although significant optimization is needed, the novel process shows great promise.

Hydrolysis of organic wastewater particles in laboratory scale and pilot scale biofilm reactors under anoxic and aerobic conditions

1998 ◽  
Vol 38 (8-9) ◽  
pp. 179-188 ◽  
Author(s):  
K. F. Janning ◽  
X. Le Tallec ◽  
P. Harremoës
Keyword(s):  
Organic Matter ◽  
Mass Balance ◽  
Particulate Organic Matter ◽  
Removal Rate ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Synthetic Wastewater ◽  
Aerobic Conditions ◽  
Biofilm Reactors ◽  
Hydrolysis Of

Hydrolysis and degradation of particulate organic matter has been isolated and investigated in laboratory scale and pilot scale biofilters. Wastewater was supplied to biofilm reactors in order to accumulate particulates from wastewater in the filter. When synthetic wastewater with no organic matter was supplied to the reactors, hydrolysis of the particulates was the only process occurring. Results from the laboratory scale experiments under aerobic conditions with pre-settled wastewater show that the initial removal rate is high: rV, O2 = 2.1 kg O2/(m3 d) though fast declining towards a much slower rate. A mass balance of carbon (TOC/TIC) shows that only 10% of the accumulated TOC was transformed to TIC during the 12 hour long experiment. The pilot scale hydrolysis experiment was performed in a new type of biofilm reactor - the B2A® biofilter that is characterised by a series of decreasing sized granular media (80-2.5 mm). When hydrolysis experiments were performed on the anoxic pilot biofilter with pre-screened wastewater particulates as carbon source, a rapid (rV, NO3=0.7 kg NO3-N/(m3 d)) and a slowler (rV, NO3 = 0.3 kg NO3-N/(m3 d)) removal rate were observed at an oxygen concentration of 3.5 mg O2/l. It was found that the pilot biofilter could retain significant amounts of particulate organic matter, reducing the porosity of the filter media of an average from 0.35 to 0.11. A mass balance of carbon shows that up to 40% of the total incoming TOC accumulates in the filter at high flow rates. Only up to 15% of the accumulated TOC was transformed to TIC during the 24 hour long experiment.

scholarly journals Investigation of Co–Fe–Al Catalysts for High-Calorific Synthetic Natural Gas Production: Pilot-Scale Synthesis of Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 105
Author(s):  
Tae Young Kim ◽  
Seong Bin Jo ◽  
Jin Hyeok Woo ◽  
Jong Heon Lee ◽  
Ragupathy Dhanusuraman ◽  
...  
Keyword(s):  
Natural Gas ◽  
Spinel Phase ◽  
Space Velocity ◽  
Pilot Scale ◽  
Gas Production ◽  
Laboratory Scale ◽  
Optimum Conditions ◽  
Synthetic Natural Gas ◽  
Co Conversion ◽  
Ft Ir

Co–Fe–Al catalysts prepared using coprecipitation at laboratory scale were investigated and extended to pilot scale for high-calorific synthetic natural gas. The Co–Fe–Al catalysts with different metal loadings were analyzed using BET, XRD, H2-TPR, and FT-IR. An increase in the metal loading of the Co–Fe–Al catalysts showed low spinel phase ratio, leading to an improvement in reducibility. Among the catalysts, 40CFAl catalyst prepared at laboratory scale afforded the highest C2–C4 hydrocarbon time yield, and this catalyst was successfully reproduced at the pilot scale. The pelletized catalyst prepared at pilot scale showed high CO conversion (87.6%), high light hydrocarbon selectivity (CH4 59.3% and C2–C4 18.8%), and low byproduct amounts (C5+: 4.1% and CO2: 17.8%) under optimum conditions (space velocity: 4000 mL/g/h, 350 °C, and 20 bar).

Assessment of clogging in constructed wetlands by saturated hydraulic conductivity measurements

2019 ◽  
Vol 79 (2) ◽  
pp. 314-322 ◽  
Author(s):  
F. Licciardello ◽  
R. Aiello ◽  
V. Alagna ◽  
M. Iovino ◽  
D. Ventura ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Hydraulic Conductivity ◽  
Constructed Wetlands ◽  
Spatial Scales ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Test Method ◽  
Conductivity Measurements ◽  
Multiple Spatial Scales ◽  
Ks Values

Abstract This study aims at defining a methodology to evaluate Ks reductions of gravel material constituting constructed wetland (CW) bed matrices. Several schemes and equations for the Lefranc's test were compared by using different gravel sizes and at multiple spatial scales. The falling-head test method was implemented by using two steel permeameters: one impervious (IMP) and one pervious (P) on one side. At laboratory scale, mean K values for a small size gravel (8–15 × 10−2 m) measured by the IMP and the P permeameters were equal to 19,466 m/d and 30,662 m/d, respectively. Mean Ks values for a big size gravel (10–25 × 10−2 m) measured by the IMP and the P permeameters were equal to 12,135 m/d and 20,866 m/d, respectively. Comparison of Ks values obtained by the two permeameters at laboratory scale as well as a sensitivity analysis and a calibration, lead to the modification of the standpipe equation, to evaluate also the temporal variation of the horizontal Ks. In particular, both permeameters allow the evaluation of the Ks decreasing after 4 years-operation and 1–1.5 years' operation of the plants at full scale (filled with the small size gravel) and at pilot scale (filled with the big size gravel), respectively.

scholarly journals Possibilities of the Development of Edible Insect-Based Foods in Europe

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 766
Author(s):  
Magdalena Skotnicka ◽  
Kaja Karwowska ◽  
Filip Kłobukowski ◽  
Aleksandra Borkowska ◽  
Magdalena Pieszko
Keyword(s):  
Material Processing ◽  
Functional Food ◽  
The Other ◽  
Raw Material ◽  
Edible Insects ◽  
Mineral Salts ◽  
Edible Insect ◽  
Alternative Protein ◽  
The World ◽  
The One

All over the world, a large proportion of the population consume insects as part of their diet. In Western countries, however, the consumption of insects is perceived as a negative phenomenon. The consumption of insects worldwide can be considered in two ways: on the one hand, as a source of protein in countries affected by hunger, while, on the other, as an alternative protein in highly-developed regions, in response to the need for implementing policies of sustainable development. This review focused on both the regulations concerning the production and marketing of insects in Europe and the characteristics of edible insects that are most likely to establish a presence on the European market. The paper indicates numerous advantages of the consumption of insects, not only as a valuable source of protein but also as a raw material rich in valuable fatty acids, vitamins, and mineral salts. Attention was paid to the functional properties of proteins derived from insects, and to the possibility for using them in the production of functional food. The study also addresses the hazards which undoubtedly contribute to the mistrust and lowered acceptance of European consumers and points to the potential gaps in the knowledge concerning the breeding conditions, raw material processing and health safety. This set of analyzed data allows us to look optimistically at the possibilities for the development of edible insect-based foods, particularly in Europe.

PREPARATION OF PRECIPITATED CALCIUMCARBONATE USING ADDITIVE AND WITHOUT ADDITIVE

2015 ◽  
Vol 77 (3) ◽  
Author(s):  
Anuar Othman ◽  
Nasharuddin Isa ◽  
Rohaya Othman
Keyword(s):  
Calcium Carbonate ◽  
Calcium Hydroxide ◽  
Mineral Composition ◽  
Hydrated Lime ◽  
Raw Material ◽  
Precipitated Calcium Carbonate ◽  
Uniform Size ◽  
The One

Precipitated calcium carbonate (PCC) chemically can be synthesized in the laboratory. In this study, hydrated lime or calcium hydroxide was used as raw material with sucrose as additive to produce PCC. The process was compared with the one without additive. PCC produced was observed based on morphology, mineral composition and size by using Fesem-Edx and LPSA, respectively. PCC products without additive demonstrated fine and more uniform size of calcite PCC as compared to the one with additive. Nevertheless, the process with additive produced more PCC product than without additive.

Performance of Nano-Silica Insulation Material Enhanced by High Humidity-Reinforcement Method

2016 ◽  
Vol 697 ◽  
pp. 433-436
Author(s):  
Shi Chao Zhang ◽  
Yu Feng Chen ◽  
Wei Wu ◽  
Hao Ran Sun ◽  
Guang Hai Wang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Raw Material ◽  
High Humidity ◽  
Insulation Material ◽  
Condensation Polymerization ◽  
Drying Process ◽  
Nano Silica ◽  
Insulation Materials ◽  
The One ◽  
Strength Improvement

In this paper, fumed nano-silica as the main raw material, nano-silica insulation materials were prepared by the dry processing. Research on humidity-reinforcement of nano-Silica insulation materials has been carried out and analyzed. When hygroscopicity of samples reach to 23%, the compressive strength 1.65MPa is at twice the one without high humidity-reinforcement, while the thermal conductivities are almost the same. Then, the action mechanism of high humidity-reinforcement method was analyzed. In humidity-reinforcement method, as vapor enters, silica sol is formed in the gap between one aggregate particle and another, and various condensation polymerization occurred in the drying process, which lead to aggregates connection and compressive strength improvement.

Intellectual capital and performance of listed companies: empirical evidence from Italy

2014 ◽  
Vol 18 (1) ◽  
pp. 22-35 ◽  
Author(s):  
Domenico Celenza ◽  
Fabrizio Rossi
Keyword(s):  
Explanatory Power ◽  
Value Added ◽  
Listed Companies ◽  
Cross Sectional ◽  
Content Type ◽  
Accounting Performance ◽  
And Performance ◽  
The One ◽  
Two Stages ◽  
The Relationship

Purpose – The aim of this paper is to investigate the relationship between corporate performance and Value Added Intellectual Coefficient (VAICTM) on the one hand, and the relationship between the variations in market value and the variations in VAIC on the other hand. Design/methodology/approach – Starting from the VAIC model, 23 Italian listed companies were examined with the aim of investigating the relationship between VAIC and the performance of the firms in the sample. The analysis was divided into two stages. In the first stage, eight models of linear regression were estimated to verify the presence of a positive and statistically significant relationship between M/BV and VAIC and between accounting performance indicators (ROE, ROI, ROS) and the VAIC. In the second stage, six other models were tested, considering as an independent variable the variations in VAIC and the variations in profitability indicators. Findings – The outcomes of the application stress the importance of VAIC in the explanation of the variations in MV and its role as “additional coefficient” in the analysis of equity performance. Originality/value – This methodology highlights some very interesting aspects. In particular, whereas the relationship between M/BV and VAIC and between profitability indicators (ROI, ROE, ROS) and VAIC is statistically insignificant, the subsequent analysis highlights the importance of VAIC as a variable capable of increasing the explanatory power of the regression in a cross-sectional perspective.

Sign in / Sign up

Export Citation Format

Share Document