Abstract Mining projects are often budgeted in millions of dollars, making it of interest to the investor to measure a project’s uncertainties and risks, which include the changes in the commodity price. The simulation of asset prices is valid because it enables displaying, with a degree of certainty, the future behavior of a financial asset. One of the most commonly used mathematical forecast models is the Geometric Brownian Motion (GBM) model. This article aims at simulating the forecast price of an iron ore commodity with the GBM method based on the historical price series and comparing it to other forecast approaches used in the financial market. The results of this study indicate that the model has limitations, which should be considered. However, it is an overall good tool to support the economic evaluation of a project, if performed along with other approaches.

Abstract Mine closure is the set of all activities that follow the end of the productive phase of a mine, characterizing itself as the process of returning an area transformed by mining into a new condition of sustainability, considering the potential future and the best possible reclamation of the area impacted. However, such an understanding was not conceivable during the Colonial Period, a time when gold mining took place in the Ouro Preto Hill, among others, and nearly 200 years after the end of the gold rush, negative and positive impacts are revealed by the human interaction and the urban occupation on those mined areas. Through both geographic information data of eighteenth-century mining traces and a socioeconomic study involving six tourist gold mines, this article describes how overcoming paradigms involving underground mines have resulted in business opportunities, setting a success example of Mine Closure and future use of the area, showing an alternative way to handle the current abandoned mines.

Abstract The presence of copper-bearing minerals is known to bring on many challenges during the cyanidation of gold ore, like high consumption of cyanide and low extraction of metal, which are undesirable impacts on the auriferous recovery in the subsequent process step. The high copper solubility in cyanide prevents the direct use of classical hydrometallurgical processes for the extraction of gold by cyanidation. Additionally, the application of a conventional flotation process to extract copper is further complicated when it is oxidized. As a result, an acid pre-leaching process was applied in order to clean the ore of these copper minerals that are cyanide consumers. The objective was to evaluate the amount of soluble copper in cyanide before and after acidic cleaning. From a gold ore containing copper, the study selected four samples containing 0.22%, 0.55%, 1.00% and 1.36% of copper. For direct cyanidation of the ore without pre-treatment, copper extraction by cyanide complexing ranged from 8 to 83%. In contrast, the pre-treatment carried out with sulfuric acid extracted 24% to 99% of initial copper and subsequent cyanidation extracted 0.13 to 1.54% of initial copper. The study also showed that the copper contained in the secondary minerals is more easily extracted by cyanide (83%), being followed by the copper oxy-hydroxide minerals (60%), while the copper contained in the manganese oxide is less complexed by cyanide (8% a 12%). It was possible to observe that minerals with low acid solubility also have low solubility in cyanide. Cyanide consumption decreased by about 2.5 times and gold recovery increased to above 94% after acidic pre-cleaning.