09 Intern Assignment Refractory Materials

WELCOME to WINDOWS on the INQUIRY CLASSROOM! You have landed on a piece of a National Science Foundation Project (DUE 1245730) directed by Professor Chris Bauer, Chemistry Department, University of New Hampshire. This is one part of a completely documented inquiry-based university science course called “Fire & Ice” which explores the nature of heat and temperature. There are multiple video perspectives and commentary from instructors and students, and documents of all course materials (agenda, instructions, student work). It’s too complicated to explain here. Take a look at the user orientation document at this link

The importance of mineralogical knowledge in the sustainability of artisanal gold mining: a mid-south Peru case

Mineralogy and gold processing techniques from several mining areas of the Nazca-Ocoña gold belt, Mid-South Peru, were investigated to assess the efficiency of gold extraction methods in relation to their mineralogy. The deposits from this belt are intrusion gold related to mineralization in quartz veins. Native gold occurs as micrometric grains encapsulated in pyrite and in minor amounts in other sulfides and quartz. Electrum is found mainly in fractures of pyrite and attains up to 35 wt. % Ag. In addition to these occurrences, gold tellurides also occur and they are abundant in San Luis. Gold processing is carried out by amalgamation with mercury and/or cyanidation. The comparison of the gold grade in the mineralizations and in the residual tailings indicates that a significant amount of gold is not recovered using the mercury amalgamation process and also, in the case of the gold recovery by cyanidation, except when cement was added to the cyanide solution. This was due to an increase in the pH that favours the dissolution of the gold matrix. In the cyanidation process carried out in tailings previously treated with mercury, part of the mercury retained in them is released to the atmosphere or to the cyanidation fluids.Peer ReviewedPostprint (published version

Two-phased knowledge formalisation for hydrometallurgical gold ore process recommendation and validation

This paper describes an approach to externalising and formalising expert knowledge involved in the design and evaluation of hydrometallurgical process chains for gold ore treatment. The objective was to create a case-based reasoning application for recommending and validating a treatment process of gold ores. We describe a twofold approach. Formalising human expert knowledge about gold mining situations enables the retrieval of similar mining contexts and respective process chains, based on prospection data gathered from a potential gold mining site. Secondly, empirical knowledge on hydrometallurgical treatments is formalised. This enabled us to evaluate and, where needed, redesign the process chain that was recommended by the first aspect of our approach. The main problems with formalisation of knowledge in the domain of gold ore refinement are the diversity and the amount of parameters used in literature and by experts to describe a mining context. We demonstrate how similarity knowledge was used to formalise literature knowledge. The evaluation of data gathered from experiments with an initial prototype workflow recommender, Auric Adviser, provides promising results

Idiopathic AIDS enteropathy and treatment of gastrointestinal opportunistic pathogens.

Diarrhea in patients with acquired immune deficiency syndrome (AIDS) has proven to be both a diagnostic and treatment challenge since the discovery of the human immunodeficiency virus (HIV) virus more than 30 years ago. Among the main etiologies of diarrhea in this group of patients are infectious agents that span the array of viruses, bacteria, protozoa, parasites, and fungal organisms. In many instances, highly active antiretroviral therapy remains the cornerstone of therapy for both AIDS and AIDS-related diarrhea, but other targeted therapies have been developed as new pathogens are identified; however, some infections remain treatment challenges. Once identifiable infections as well as other causes of diarrhea are investigated and excluded, a unique entity known as AIDS enteropathy can be diagnosed. Known as an idiopathic, pathogen-negative diarrhea, this disease has been investigated extensively. Atypical viral pathogens, including HIV itself, as well as inflammatory and immunologic responses are potential leading causes of it. Although AIDS enteropathy can pose a diagnostic challenge so too does the treatment of it. Highly active antiretroviral therapy, nutritional supplementation, electrolyte replacements, targeted therapy for infection if indicated, and medications for symptom control all are key elements in the treatment regimen. Importantly, a multidisciplinary approach among the gastroenterologist, infectious disease physician, HIV specialists, oncology, and surgery is necessary for many patients

A Detailed Analysis of the Productivity Performance of Mining in Canada

In recent years, the productivity performance of mining in Canada has been very poor. Based on official real GDP and labour input estimates from Statistics Canada, labour productivity in mining fell by 2.21 per cent per year between the 2000 cyclical peak and 2007, with capital productivity down 0.28 per cent per year and total factor productivity (TFP) off 1.07 per cent per year between 2000 and 2006. Among the various hypotheses put forward to explain these trends, the most robust seems to be that higher output prices have suppressed productivity growth through two effects: increased exploitation of low-productivity marginal resource deposits, and business decisions based on profitability rather than productivity. Despite the decline in productivity in mining, it is not necessarily true that Canadians are worse off. In fact, increased relative output prices for mining products as well as a high productivity level in the mining sub-sector, have resulted in positive contributions to Canada‟s aggregate labour productivity growth from 2000 to 2006 and an offsetting effect on the post-2000 aggregate labour productivity slowdown.productivity, mining, labour productivity, output per hour, capital intensity, total factor productivity, Canada, resource extraction

Gold recovery : effect of ozonation on refractory gold ores prior to cyanidation

Abstract: Mineral processing of refractory gold ore is uneconomical through conventional processing methods. The ore recovery is normally below 80% due to sulphide encapsulated gold and result into high reagent consumption by carbonates. This study was conducted to investigate the use of ozone to the existing pre-treatment processes to increase the gold recoveries. To achieve this, ozone gas was bubbled in slurry at different pH values to establish the optimal pH. The resulting residue was subjected to cyanidation and Resin in Pulp (RIL) leaching to assess the effect of ozonation on gold leaching and reagent consumption. The results obtained showed that ozonation at pH 2 for 4 hours increased gold recoveries from 10% to 70%. Base metals such as arsenic, zinc and manganese were found to leach during ozonation with a recovery of 37%, 32% and 51% respectively. Ozonation improved recoveries from refractory ores with minimal cyanide and lime consumption and can prevent preg-robbing

Recovering the lost gold of the developing world : bibliographic database

This report contains a library of 181 references, including abstracts, prepared for Project R 7120 "Recovering the lost gold of the developing world" funded by the UK' s Department for International Development (DFID) under the Knowledge and Research (KAR) programme. As part of an initial desk study, a literature review of gold processing methods used by small-scale miners was carried out using the following sources; the lSI Science Citation Index accessed via Bath Information and Data Services (BIDS), a licensed GEOREF CD-ROM database held at the BGS's Library in Keyworth and IMMage a CD-ROM database produced by the Institution of Mining and Metallurgy held by the Minerals group ofBGS. Information on the search terms used is available from the author

Wetland-based passive treatment systems for gold ore processing effluents containing residual cyanide, metals and nitrogen species

Gold extraction operations generate a variety of wastes requiring responsible disposal in compliance with current environmental regulations. During recent decades, increased emphasis has been placed on effluent control and treatment, in order to avoid the threat to the environment posed by toxic constituents. In many modern gold mining and ore processing operations, cyanide species are of most immediate concern. Given that natural degradation processes are known to reduce the toxicity of cyanide over time, trials have been made at laboratory and field scales into the feasibility of using wetland-based passive systems as low-cost and environmentally friendly methods for long-term treatment of leachates from closed gold mine tailing disposal facilities. Laboratory experiments on discrete aerobic and anaerobic treatment units supported the development of design parameters for the construction of a field-scale passive system at a gold mine site in northern Spain. An in situ pilot-scale wetland treatment system was designed, constructed and monitored over a nine-month period. Overall, the results suggest that compost-based constructed wetlands are capable of detoxifying cyanidation effluents, removing about 21.6% of dissolved cyanide and 98% of Cu, as well as nitrite and nitrate. Wetland-based passive systems can therefore be considered as a viable technology for removal of residual concentrations of cyanide from leachates emanating from closed gold mine tailing disposal facilities

Application of alternative lixiviants for secondary heap leaching of gold

Some preliminary results on the secondary leaching of previously heap leached gold ore are presented. Alternative lixiviants for gold comprising chlorine, thiourea and thiosulphate were compared with cyanide using bottle roll tests. Chlorine was subsequently selected for column leaching tests. Column tests at 1.0, 0.1 and 0.01 gL-1 Cl2 at pH 2 were conducted. The results indicated that about 23 per cent of the gold was leached over 45 days using 1 gL-1 Cl2 at pH 2. The experiments conducted proved that the chlorine/chloride system has good potential for further extraction of gold and silver from the existing cyanide heap leach residues and a process for secondary leaching of gold has been proposed. Further testwork is recommended to extend conditions, sample types, and the duration of leaching period