Biomass Production and Inoculation of Industrial Bioleaching Processes

2013 ◽  
Vol 825 ◽  
pp. 296-300 ◽  
Author(s):  
Pilar Parada ◽  
Pedro Morales ◽  
Roberto Collao ◽  
Roberto A. Bobadilla-Fazzini ◽  
Ricardo Badilla
Keyword(s):  
Microbial Activity ◽  
Residence Time ◽  
High Concentration ◽  
Industrial Operations ◽  
Continuous Regime ◽  
Nominal Capacity ◽  
Early Expression ◽  
Leaching Solution ◽  
Sulfur Oxidizing ◽  
Time Required

Microbial activity inleaching processes accounts for 4% of today’s copper produced in the world. Factorsrelated with lesser overall metal recoveries, no recovery of precious metalsand molybdenum in comparison with conventional concentration/smelting &refining technologies and the high prices of metals inhibit the use of bioleachingat a larger scale. In order to increase bioleaching rates and overall metal recoveries,continuous inoculation of the ore with a leaching solution containing specific adaptedconsortium of microorganisms, allows an early expression of microbial activity,reducing 2-3 fold the time required by ore native bearing microflora to grow.This leaching solution concentrated in microorganisms can be produced by meansof bioreactors operated in continuous regime. Unfortunately biomining microorganisms have a very low duplication timewhen comparing to common microbes like E.colior B. subtilis, that forces the useof huge volume bioreactors in the case of conventional bioreactors, to ensurethe growth of microorganisms have sufficient residence time. To overcome thisproblem, we have designed a very efficient air-lift bioreactor (Patent Registration No. CL 48319), that can be used at industrial operations for the production ofsolutions with a high concentration of biomining microorganisms, for theinoculation of bioleaching heaps, with lesser residence time in comparison toconventional bioreactors. Ourbioreactor has an internal recirculation for producing sulfide-ore bioleachingsolutions, with a phase-separating and solids-recirculation system, without theneed to impel the suspension containing the solids towards the bioreactor withpumps, using diatomaceous earth, ferric precipitates and/or elemental sulfur asa solid support to immobilize iron and/or sulfur-oxidizing microorganisms. Dependingon the source of energy supplied for the growth of the microorganisms, thebioreactor can produce either a solution concentrated in ferric ions andiron-oxidizing bacteria or sulfur oxidizing bacteria. In order to validate ourbioreactor design at industrial scale, a trial was carried out in an air-liftbioreactor of 35 m3 nominal capacity, which is part of a biomassplant located in Radomiro Tomic Division of CODELCO. In this article, theresults of the test proving the advantages and satisfactory design of ourbioreactor for producing continuously iron-oxidizing bacteria and sulfuroxidizing bacteria for inoculation and irrigation of heaps and dumps are shown.

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.

Effect of Increased Acid Concentration on the Microbial Population Inhabiting an Industrial Heap Bioleaching Plant

2013 ◽  
Vol 825 ◽  
pp. 348-351 ◽  
Author(s):  
Victor J. Zepeda ◽  
Dina Cautivo ◽  
Pedro A. Galleguillos ◽  
Camila N. Salazar ◽  
Antonio Velásquez ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Most Probable Number ◽  
Rrna Gene ◽  
Elevated Concentration ◽  
Microbial Culture ◽  
Probable Number ◽  
Dna And Rna ◽  
Heap Bioleaching ◽  
Sulfur Oxidizing ◽  
Process Solutions

The material treated in the industrial heap bioleaching plant at Escondida Mine includes sulfide, oxide and mixtures of run of mine ore (ROM) with 5% of total copper average grade. The design of the heap considers seven lifts of eighteen meters height each. Nowadays, the heap is being operated with ore loaded in the second and third lifts. The amount of acid required for the process can be increased by increasing the height of the heap and also by the characteristics of the ore. This effect can be attributed to the increase of contact time between ore and solution. The goal of this work was to assess the effect of using raffinate solution with elevated concentration of acid on a microbial culture obtained from process solutions. Reactor tests of culture grown in industrial raffinate solution were performed and DNA and RNA were extracted for qPCR and RT-qPCR analyses, respectively. A design of experiment (DOE) was considered to determine the number of replicates in order to assess the effect of two concentrations of sulfate (80 and 100 g/L) and two incubation temperatures (30 and 45 °C). In addition, analysis of the Most Probable Number (MPN) of iron and sulfur oxidizing organisms and oxidation tests were used to determine the microbial activity in the tests. The results obtained from the DOE showed that acid, temperature and the interaction of temperature and energy source had a significant effect on the microbial activity. Both iron and sulfur oxidizing activities decreased when acid was added at elevated concentration. By other hand, molecular analyses showed differences in levels of specific concentrations of microorganisms and the expression of 16S rRNA gene of the different species thriving in the culture tests.

Coupling of anodic oxidation and adsorption by granular activated carbon for chemical oxygen demand removal from 4,4′-diaminostilbene-2,2′-disulfonic acid wastewater

2010 ◽  
Vol 62 (11) ◽  
pp. 2669-2677 ◽  
Author(s):  
Lizhang Wang ◽  
Yuemin Zhao
Keyword(s):  
Activated Carbon ◽  
Chemical Oxygen Demand ◽  
Residence Time ◽  
Applied Voltage ◽  
Oxygen Demand ◽  
Granular Activated Carbon ◽  
Cod Removal ◽  
Disulfonic Acid ◽  
High Concentration ◽  
Solution Ph

Experiments were performed to reduce chemical oxygen demand (COD) from 4,4′-diaminostilbene-2,2′-disulfonic (DSD) acid manufacturing wastewater using electrochemical oxidation coupled with adsorption by granular activated carbon. The COD removal is affected by the residence time and applied voltage. When the residence time is increased, lower value of COD effluent could be obtained, however, the average current efficiency (ACE) decreased rapidly, and so does the applied voltage. In addition, aeration could effectively enhance COD removal efficiency and protect anodes from corrosion. Furthermore, the acidic condition is beneficial to the rapid decrease of COD and the values of pH effluent are independent of the initial solution pH. The optimization conditions obtained from these experiments are applied voltage of 4.8 V, residence time of 180 min and air–liquid ratio of 4.2 with the COD effluent of about 690 mg L−1. In these cases, the ACE and energy consumption are 388% and 4.144 kW h kg−1 COD, respectively. These perfect results from the experiments illustrate that the combined process is a considerable alternative for the treatment of industrial wastewater containing high concentration of organic pollutants and salinity.

Bio-Heap Leaching of Primary Copper Sulfide Ore by JOGMEC

2017 ◽  
Vol 262 ◽  
pp. 99-102
Author(s):  
Tatsuya Shinkawa ◽  
Tadashi Chida ◽  
So Furukawa ◽  
Taro Kamiya
Keyword(s):  
Copper Sulfide ◽  
Heap Leaching ◽  
Sulfide Ores ◽  
High Iron Content ◽  
Iron Oxidizing Bacteria ◽  
Acid Consumption ◽  
Sulfide Ore ◽  
Leaching Solution ◽  
Sulfur Oxidizing ◽  
Copper Sulfide Ore

JOGMEC has been carrying out the study on primary copper sulfide ores leaching for recovering copper economically and efficiently by heap leaching. In our study, we have been using the primary copper sulfide ore produced in an IOCG deposit. The ore is characterized by high iron content and high acid consumption in leaching. For the optimization of the leaching, the conditions such as ore size, agglomeration, pH and irrigation rate of leaching solution were examined with column leach tests. The best result was over 80 % extraction of copper in 150 days with leaching solution of 1 M sulfuric acid and temperature of 45 °C. In this experiment, the fines of the ore sample were removed before putting it into the column to keep the permeability of the ore bed. In these column leach tests, the Fe2+/total-Fe ratio of PLS decreased gradually by the activity of naturally grown iron-oxidizing bacteria. The bacteria in PLS, which have the ability of iron-oxidizing and sulfur-oxidizing, were identified by next-generation sequencing as Acidithiobacillus caldus and Sulfobacillus thermosulfidooxidans. We also carried out bench-scale tests with about 200 tons of the primary copper sulfide ores. Iron-oxidizing and sulfur-oxidizing bacteria were identified in the leaching solution as same with column leach tests. It is considered that the bacteria worked in the leaching solution and on the surface of the ores.

Removal of Organic Matters in Pesticide Wastewater by Supercritical Water Oxidation

2014 ◽  
Vol 955-959 ◽  
pp. 2340-2348 ◽  
Author(s):  
Dong Hai Xu ◽  
Shu Zhong Wang ◽  
Chuan Bao Huang ◽  
Xing Ying Tang ◽  
Yang Guo ◽  
...  
Keyword(s):  
Chemical Oxygen Demand ◽  
Residence Time ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Oxygen Demand ◽  
Reaction Pathways ◽  
Experimental Plant ◽  
Supercritical Water Oxidation ◽  
High Concentration ◽  
Organic Matters

Supercritical water oxidation (SCWO) is an alternative to effectively dispose many varieties of organic wastewaters. In this article, a high concentration pesticide wastewater with very complicated components was handled by SCWO in a batch experimental plant at 25 MPa, 410–580 °C within the oxidant coefficient of 1.1–4.0 and the residence time of 1.0–10.0 min. The results show that reaction temperature, oxidant coefficient, residence time can improve XCOD(removal efficiency of chemical oxygen demand) of reactor effluent. XCODreaches up to 99.89% at 550 °C, 25 MPa with the oxidant coefficient of 3.0 and the residence time of 5.0 min, and the corresponding COD concentration is 73 mg/L. Residence time indicates a relatively more important influence on COD1at higher reaction temperatures and OCs. Furthermore, possible reaction pathways for SCWO of organic matters in the pesticide wastewater were also proposed primarily.

Numerical prediction of the performance of horizontal sand filters as the pitch of the spiral protrusion changes

2013 ◽  
Vol 67 (10) ◽  
pp. 2249-2256
Author(s):  
Ruth Mossad ◽  
Hal Aral
Keyword(s):  
Residence Time ◽  
Flow Rate ◽  
Numerical Prediction ◽  
Sand Filters ◽  
Ansys Fluent ◽  
Sand Filter ◽  
Flow Channels ◽  
Fluent Software ◽  
Time Required ◽  
Nonlinear Fashion

The height of vertical sand filters are limited due to their structural cost. A horizontal sand filter may offer a better alternative; however, flow channels to the least resistance zone generated at the top of the filter as the sand gets wet and settles. A horizontal sand filter, internally baffled with spiral protrusion, is numerically modelled to study the effect of these spirals in reducing the channelling and enhancing the filter's effectiveness. Three different spiral pitches, 1.0, 0.75, and 0.5 m have been numerically modelled using Ansys FLUENT software. The parameters investigated were the power needed to run a flow rate through the horizontal filter and the residence time. The results show that as the spiral pitch decreases, the channelling reduces while the power increases. The power needed to pump a given flow rate of water in a 10 m long horizontal filter in all three cases investigated was less than the power needed to pump the same flow rate to the top of a 10 m long vertically standing sand filter. Results also showed that the time required for the flow to traverse through the sand filter increases in a nonlinear fashion as the pitch size decreases; however, the effectiveness of the filter increases.

scholarly journals Comparative Virulence of Metarhizium anisopliae and Four Strains of Beauveria bassiana Against House Fly (Diptera: Muscidae) Adults With Attempted Selection for Faster Mortality

2021 ◽  
Author(s):  
Roxie L White ◽  
Christopher J Geden ◽  
Phillip E Kaufman ◽  
Dana Johnson
Keyword(s):  
Beauveria Bassiana ◽  
Metarhizium Anisopliae ◽  
House Fly ◽  
The Other ◽  
Biological Control Agents ◽  
High Concentration ◽  
House Flies ◽  
Lethal Time ◽  
Selection For ◽  
Time Required

Abstract Entomopathogenic fungi such as Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae/brunneum (Metchnikoff)/Petch have shown promising results for managing the house fly, Musca domestica L. A primary challenge of using these biological control agents (BCAs) in field situations is the time required to induce high adult house fly mortality, typically 6–7 d post-exposure. In this study, virulence of M. anisopliae (strain F52) and four B. bassiana strains were compared. The B. bassiana strains GHA and HF23 are used in commercial products and those were compared with two strains that were isolated from house flies on dairy farms (NFH10 and L90). Assays were conducted by exposing adult house flies to fungal-treated filter paper disks for 2 h. The lethal time to 50% mortality (LT50) at the high concentration of 1 × 109 conidia ranged from 3.8 to 5.2 d for all five strains. GHA, NFH10, and L90 killed flies faster than M. anisopliae strain F52; HF23 did not differ from either the M. anisopliae or the other B. bassiana strains. Attempts with the NFH10 strain to induce faster fly mortality through selection across 10 fungal to fly passages did not result in shorter time to fly death of the selected strain compared with the unselected strain.

Efficient generation of mixed oxidant disinfectants: parametric study on electrode materials and operating conditions

2015 ◽  
Vol 15 (6) ◽  
pp. 1179-1186 ◽  
Author(s):  
Longnan Li ◽  
Daejoong Kim
Keyword(s):  
Residence Time ◽  
Electrode Materials ◽  
Electrochemical Cell ◽  
Electrode System ◽  
Operating Conditions ◽  
Inflow Rate ◽  
Oxidation Reactions ◽  
High Concentration ◽  
Maximum Value

Electrochemical disinfection is an efficient method used for treatment of drinking water. It has great environmental compatibility as compared to conventional disinfection methods. In this study, the effects of the electrode materials and working conditions were investigated. The experimental results show that the type 1 (iridium oxide-coated anode and cathode) electrode system generated a high concentration of free available chlorines (FACs) because iridium has higher electrocatalytic activity than ruthenium. When the applied voltage increases, the acceleration of oxidation reactions in the electrochemical cell resulted in the increased generation of FACs. The solution inflow rate is approximately inversely proportional to the residence time of the salt solution in the electrochemical cell. A long residence time can induce a higher FAC generation. In addition, the production of FACs is increased with the decreasing electrode open ratio (a/A). With a/A > 0 and a lower inflow rate, the FAC concentration tends to approach a maximum value because of by-product generation. The ozone species generated in the electrochemical cell were determined by the maximum voltage. The electrode open ratio affected the ozone generation rate due to the mixing effect of cathode products.

Turbulent Convergent Tidal Fronts

1974 ◽  
Vol 54 (2) ◽  
pp. 469-479 ◽  
Author(s):  
R. D. Pingree ◽  
G. R. Forster ◽  
G. K. Morrison
Keyword(s):  
Residence Time ◽  
Water Depth ◽  
Tidal Mixing ◽  
Frontal Region ◽  
English Channel ◽  
High Concentration ◽  
Tidal Front ◽  
Channel Temperature ◽  
Visual Observations

A high concentration of certain planktonic animals was found in a frontal region in the English Channel. Temperature, salinity and current measurements and direct visual observations (underwater) describe the nature of the front. It is shown that water depth, season, strong tidal mixing and residence time are important factors leading to the formation and maintenance of a turbulent convergent tidal front.

Inter-Operator Variability Effects on Quality and Productivity

1981 ◽  
Vol 25 (1) ◽  
pp. 551-551
Author(s):  
Steven L. Johnson
Keyword(s):  
Individual Differences ◽  
Normal Operator ◽  
Limited Information ◽  
Productivity Improvement ◽  
Potential Productivity ◽  
Entry Level ◽  
Repair Costs ◽  
Industrial Operations ◽  
Time Required ◽  
The Impact

The paper discusses the magnitude of differences among individual operators and the effect of those differences on two areas of particular interest today: productivity and product quality. The focus of the paper is on the impact of individual differences on paced (i.e. machine-paced) operations. There has been an extensive amount of work conducted on individual differences, particularly within the psychological literature. However, most of this work has been conducted in laboratories using well controlled (i.e. often simplified) tasks, rather than the generally more complex tasks representative of industrial operations. In addition, the subjects in these studies have often been college students that are not representative of the industrial workforce. The studies that have been conducted on actual manufacturing or assembly operations with industrial operators have exhibited interesting results. The differences among operators that are of particular importance to the present paper are the differences in the time required to complete a task. That is, for a given manufacturing or assembly operation, there is a distribution of times necessary to complete the task by different operators. The dispersion of this type of distribution has been specified in many ways (e.g. standard deviation, coefficeint of variation, range, etc.) The measure that most authors have used, and one that is readily interpretable, is the ratio of the fastest to the slowest operator in terms of the time required. The conclusions of many different studies in many different environments are very similar. The ratio of the fastest (shortest time) to the slowest (longest time) is generally between 1:2.0 and 1:2.5. The problem, therefore, is that if the slowest individual performing an operation (e.g. assembly line) takes twice as long as the fastest, how long should be allotted to perform the job if it is a paced operation? The standard answer provided by Time Study Engineers (and textbooks) is “pick the normal operator.” When asked to define “normal” the usual response refers to the “average” operator. However, if a paced operation is set for the average (i.e. mean) operator, then 50 percent of the workforce would be unable to perform the task. This is not desirable and is, in fact, not the case. Pursuing the issue further, the question could be asked, “What proportion of the workforce can not perform the task in the allotted time?” To this question, the answer is essentially always less than ten percent and is often less than five percent. The implications of the distribution among operators in a paced operation are neither subtle nor inconsequential. The operators who are slower than the fixed pace have one or more of the following alternatives. One alternative is attrition by moving to a different job. A problem with this, however, is that many of the paced operations today are entry level jobs and movement requires seniority. A second alternative is to compromise safety precautions, such as removing guards or taking shortcuts that are considered to be unsafe, although they might take less time. A third alternative is to not complete the task (five screws instead of six), thus reducing the quality of the product and/or increasing repair costs. The alternatives listed above are some of those possible for the slower operator. However, for a fixed paced line (e.g. set so that only 10 percent are not able to complete the task), what are the implications for the group of operators who could perform the operation faster. That is, if only 10 percent can not accomplish the task, then 90 percent could perform it faster but are not allowed to in a paced operation. This obviously has severe implications for the productivity of an operation. If the ratio of the fastest to the slowest operator is 1:2.0 (a conservative estimate according to the literature) and the allowed time is set for the tenth-percentile operator, then productivity could be improved by approximately 17 percent by using a self paced operation. Although self-paced (actually non-machine paced) systems have additional costs (e.g. more costly conveyance, more in-process material, etc.), the benefits derived from the potential productivity improvement are considerable. The purpose of the present paper is threefold. First, it is to reiterate the fact that inter-operator differences (as well as intra-operator differences) do exist in industry, as well as in laboratories. Second, the differences that exist in industry today are not small (e.g. in the range of 1:2.0 to 1:2.5). Third, there are serious implications resulting from operators who can not perform their job in the allotted time (e.g. attrition, safety, and quality). Fourth, the resultant loss in productivity due to paced operations that do not accommodate individual differences among operators is not trivial (e.g. 17 percent or greater). The area of inter-operator variability is an area that needs more investigation. However, even with the present limited information on the topic, there are important improvements that are possible in industry today by utilizing difference in capabilities instead of ignoring them.

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