293,535 research outputs found
Cariboo Amalgamated Gold Mines Limited:
No full textCariboo Amalgamated Gold Mines Limited (Non-Personal Liability), owning outright and developing approximately 175 mineral claims in the Barkerville area, Cariboo Mining District, formerly owned by Fred M. Wells, Esq
Informal gold mining and mercury pollution in Brazil
No full textThe Amazon region has been responsible for a major share of Brazilian gold production in recent years. The region has witnessed a sizable gold rush comparable only to the California gold rush last century. The gold rush has spawned a powerful informal mining sector and has attracted many people - some who have come to the region in search of wealth and some who were already there but were displaced from other, unsuccessful economicactivities. What these people encounter at the mining sites are dreadful living and working conditions. Gold mining also causes substantial environmental problems, which may persist whether gold deposits do or not. The author discusses the environmental effects of gold mining in the region, focusing on mercury pollution. Mercury, an important input in gold extraction, is being discharged into the atmosphere and the rivers at alarming rates. The environmental costs of the present extraction, is being discharged into the atmosphere and the rivers at alarming rates. The environmental costs of the present extraction technology will be faced primarily by future generations, because of natural chemical processes. Although removing the mercury already discharged from the Amazonian environment may be an enormous task, at least future discharges should be curtailed through the use of appropriate technology, environmental education, and a combination of command and control measures and market-based incentives. The author describes the gold extraction process and the extent of mercury use and contamination. He analyzes key elements of the environmental problem, especially the informal miner and the fish economy. Finally, he suggests a combination of command and control regulations and market-based incentives adapted to the informal gold mining economic environment. He emphasizes the need for an education campaign about the perils of using mercury and the availability of more appropriate, and inexpensive, alternative extraction technologies.Mining&Extractive Industry (Non-Energy),Montreal Protocol,Water and Industry,Coastal and Marine Resources,Primary Metals
Catalytic oxidation of ethanol on gold electrode in alkaline media
No full textThis work presents a study of the catalytic oxidation of ethanol on polycrystalline gold electrode in alkaline media. The investigation was carried out by means of chronoamperometry, cyclic voltammetry, and in situ FTIR spectroscopy. The main goal was to investigate the early stages of ethanol electrooxidation, namely at fairly low potentials (E = 600 mV vs. RHE) and for moderate reaction times (t < 300 s). Chronoamperometric experiments show a current increase accompanying the increasing in the ethanol concentration up to about 2 M and then a slight decrease at 3 M. Adsorbed CO has been observed as early as about 200 mV vs. RHE and indicates that the cleavage of the C-C bond might occur, probably to a small extent, at very low overpotentials during ethanol adsorption on gold surface. The amount of dissolved acetate ions produced during the chronoamperomentry was followed by the asymmetric stretching band at 1558 cm(-1) as a function of time, and found to increase linearly with time up to 300 s. This allowed estimating the reaction order of acetate formation with respect to ethanol concentration
Gold Monetization and Gold Discipline
No full textThe paper is a study of the price level and relative price effects of a policy to monetize gold and fix its price at a given future time and at the then prevailing nominal price. Price movements are analyzed both during the transition to the gold standard and during the post-monetization period. The paper also explores the adjustments to fiat money which are necessary to ensure that this type of gold monetization is non-inflationary. Finally, some conditions which produce a run on the government's gold stock leading to the collapse of the gold standard and the timing of such a run are examined.
Rheumatoid arthritis, gold therapy, contact allergy and blood cytokines.
No full textOBJECTIVE: To study the clinical and biochemical effects of a low starting dose for gold therapy in rheumatoid arthritis patients with a contact allergy to gold. METHODS: Serum cytokines were assayed before and 24 h after the first injection of gold sodium thiomalate (GSTM). RESULTS: Contact allergy to gold was found in 4 of 19 patients. Compared to gold-negative patients (starting dose: 10 mg GSTM), there was a larger increase in serum TNFalpha (p < 0.05), sTNF-R1 (NS), and IL-1 ra (p < 0.05) in gold-allergic patients. CONCLUSIONS: Cytokines are released in blood by GSTM in RA patients with gold allergy. To minimize the risk of acute adverse reactions the starting dose of GSTM should be lowered to 5 mg. Alternatively, patients should be patch-tested before gold therapy; in test-positive cases, 5 mg is recommended as the first dose
Is Gold a Hedge or a Safe Haven? An Analysis of Stocks, Bonds and Gold
No full textThis paper addresses two questions. First, we investigate whether gold is a hedge against stocks and/or bonds and second, we investigate whether gold is a safe haven for investors if either stocks or bonds fall. A safe haven is defined as a security that loses none of its value in case of a market crash. This is counterpoised against a hedge, defined as a security that does not co-move with stocks or bonds on average. We study constant and time-varying relationships between stocks, bonds and gold in order to investigate the existence of a hedge and a safe haven. The empirical analysis examines US, UK and German stock and bond prices and returns and their relationship with the Gold price. We find that (i) Gold is a hedge against stocks, (ii) Gold is a safe haven in extreme stock market conditions and (iii) Gold is a safe haven for stocks only for 15 trading days after an extreme shock occurred.Safe haven, gold, stock-bond correlation, flight-to-quality
Gold in the investment portfolio
No full textThe paper examines the key drivers of gold investment. Since 2000 the gold price has risen drastically, making gold an interesting add-on to a portfolio. As gold futures have negative roll returns, gold pool accounts are characterized by high credit risk and physical possession of gold means high transaction costs, Xetra-Gold might be the most efficient way to enter the market. Xetra-Gold is a product created by the Deutsche Börse in 2007, which is handled like a security but can be exchanged into physical gold any time. In the portfolio context gold has had a positive impact on Euro and USD portfolios between 2000 and 2006 due to considerable returns and low correlation to other assets. However, this has not been true for almost all other periods, the correlation was always low but the returns of gold were almost zero, overriding the positive diversification effect. --Investing in gold,gold in the portfolio,correlation of gold,returns of gold,Xetra-Gold
Stuck on Gold: Real Exchange Rate Volatility and the Rise and Fall of the Gold Standard
No full textDid adoption of the gold standard exacerbate or diminish macroeconomic volatility? Supporters thought so, critics thought not, and theory offers ambiguous messages. A hard exchange-rate regime such as the gold standard might limit monetary shocks if it ties the hands of policy makers. But any decision to forsake exchange-rate flexibility might compromise shock absorption in a world of real shocks and nominal stickiness. A simple model shows how a lack of flexibility can be discerned in the transmission of terms of trade shocks. Evidence on the relationship between real exchange rate volatility and terms of trade volatility from the late nineteenth and early twentieth century exposes a dramatic change. The classical gold standard did absorb shocks, but the interwar gold standard did not, and this historical pattern suggests that the interwar gold standard was a poor regime choice.
Recovery of gold from thiosulfate solutions and pulps with anion-exchange resins
No full textWith growing environmental and occupational safety concerns over the use of cyanide in gold processing, more acceptable alternatives are receiving increased interest. The most promising of the possible alternatives is thiosulfate. However, as activated carbon is not an effective substrate for the adsorption of the gold thiosulfate complex, the thiosulfate process lacks a proven in-pulp method for recovering dissolved gold. Anion exchange resins offer a possible route for in-pulp recovery. This thesis describes work aimed at evaluating the effectiveness of commercially available anion exchange resins for the recovery of gold from thiosulfate leach liquors and pulps.
It was found that Strong-base resins are superior at accommodating the gold thiosulfate complex compared to Weak-base resins, which means Strong-base resins have a greater capacity to compete with other anions in leach solutions. Strong-base resins were therefore the preferred choice of resin for recovery of gold from thiosulfate leach solutions and pulps. Work with a selected commercial Strong-base resin showed that competing polythionates (particularly tri- and tetrathionate) lower the maximum possible loading of gold but that gold is selectively recovered over other base-metal anions in typical leach solutions. From kinetic experiments, it was found that competing polythionates did not affect the initial rate of loading of gold but displaced the loaded gold at long times. Thus it would be important to minimise the contact time of the resin with the pulp.
Equilibrium loading isotherms of gold in the presence of competing anions could be analysed by treating the ion exchange reaction as a simple chemical reaction. However, a stoichiometry and equilibrium quotient which does not follow that normally used for anion exchange, was required to describe the experimental data. A single value for the equilibrium constant also cannot be used to describe the data over the range of concentrations for a given competing anion. The order of selectivity of the anions for the anion exchange resin could be explained by the difference in structure and the charge of each anion.
The rate of loading of gold is controlled by mass transport in the aqueous phase in the presence of weakly competing anions such as sulfate and thiosulfate. An attempt was made to describe the more complex loading curves obtained in the presence of stronger competing anions such as sulfite, trithionate and tetrathionate in which it was found that the loading of gold increased to a maximum before declining to a lower equilibrium value. The difference in the rate of loading between the macroporous and gel anion exchange resins was explained by the difference in the location of their functional groups.
Operation of a small-scale resin-in-pulp plant showed that gold could be recovered from a leach pulp to yield loadings of gold of up to 6000 mg L-1 and loadings of copper below 100 mg L-1. Under ideal conditions, the gold concentration in the barren pulp could contain less than 0.01 mg L-1. Throughout the trial it was shown that loaded copper would be displaced by gold which would result in the loading of copper falling from 2000 mg L-1 in the last stage to lower than 100 mg L-1 on the resin in the first stage. It was observed that some of the dissolved gold precipitated or adsorbed on the solids during leaching. Some of this adsorbed gold was found to be recovered by the anion exchange resins that would have reported to the tails if a solid/liquid separation method was employed.
Gold was efficiently eluted with a nitrate solution and the two-step elution process using aerated ammonia followed by nitrate effectively stripped all the copper and gold from the resin. This process was found not to materially affect the equilibrium gold concentration on the resin after eight cycles, thus allowing the resin to be recycled without the need for regeneration. Electrochemical studies showed that the gold thiosulfate complex was reduced on stainless steel from a nitrate solution. Conventional electrowinning could therefore be used to recover the gold from the eluant
Gold nanoprobes for theranostics
No full textGold nanoprobes have become attractive diagnostic and therapeutic agents in medicine and life sciences research owing to their reproducible synthesis with atomic level precision, unique physical and chemical properties, versatility of their morphologies, flexibility in functionalization, ease of targeting, efficiency in drug delivery and opportunities for multimodal therapy. This review highlights some of the recent advances and the potential for gold nanoprobes in theranostics
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