Giorgio de Tomi

An estimation of the artisanal small-scale production of gold in the world.

The increase in gold price of over 400% between 2002 and 2012, due to a shift towards safe investments in a period of crisis in the global economy, created a rapid increase in gold production. A response to this shift in production was observed for artisanal and small-scale mining (ASM) units in remote locations of the world, but this phenomenon has not been quantified yet. The work presented here was done to provide a quantitative tool for estimation of the gold (Au) produced by ASM and the population of workers involved in the production process, and assessment of mercury (Hg) consumed. The following hypotheses were addressed: i) It is possible to estimate, on first approximation, the amount of Au production in the world by artisanal mining; ii) Au production by artisanal mining varies by country and continent and iii) Hg consumption due to ASM can be correlated with the methods applied in the different countries and continents for the production of Au. To do this we estimated the number of miners, calculated the change in Au price and production and then applied an adjustment factor to calculate Hg production by country and continent. The amount of Au produced depends on technology of the miners by continents (highest in South America, medium in Asia and Central America, and lowest in Africa), and the geologic setting (not investigated here). The results of the estimation show that, as of 2011, over 16 million Artisanal Miners, in the world, were involved in gold extraction (mining or treatment), producing between 380 and 450 t of gold per year, with clear global behavior between the continents in terms of recovery efficiency, confirmed by data on Hg release that is higher in countries with lower technology.

Metodologia para estimativa e gestão da produtividade de lavra

Even with the financial crisis of 2008, the steel consumption forecast for the BRIC countries - Brazil, Russia, India and China - is for a significant increase over the next decades, due to their present low per-capita consumption level. The start up of new mines to supply this increase in demand is likely to be limited due to legal and practical restrictions related to environmental, social, manpower and energy issues. Therefore, most of the new demand for iron ore will be supplied by increasing the productivity of mines currently in operation. The main challenges for managing mine productivity are related to the choice of the estimation method, due to the difficulties in collecting appropriate information and to the establishment of a representative model. This article presents an estimation approach for mine productivity estimation through multiple regressions over the operational database of the mine. The approach is proposed through a Mine Productivity Estimation and Management tool (MPEM) which can deliver savings related to increased production efficiency by the identification and removal of losses in the mine production flow. Production improvement has been actually achieved in practical applications by managing the discrepancies in the KPIs of different operating shift crews. The operational variables have been identified directly over the operational database of the mine and the model has been developed in a simple and easy-to-use fashion, with excellent levels of correlation between the estimated and actual values of the mines productivity. The article describes the development approach as well as the application of the model in a case-study.

Efficiency as a Road to Sustainability in Small Scale Mining

The world is going through a new-millennium rush in precious metals, especially gold. The great increase in gold price in the last years, probably due to a shift towards safe investments in a period of crisis in the global economy, created a rapid increase in gold production. The faster response to this shift in production came from Artisanal (ASM) and Small-scale (SSM) mining units in remote locations of the world, and Brazil is one of the main countries that has ASM and SSM on its territory. The present paper draws some definitions of Small-Scale Mining and Artisanal Mining, based on its productivity and its actual social and environmental implications, and of their sustainability. The analysis of production data of Small Scale and Large Scale Mining on global scale and on Brazilian scale shows the high potential of SSM in dealing with lower mineral grades and market fluctuations, due to its high flexibility. A general growth of the role of SSM in precious metals production in the next decades is foreseen. An elaboration on world ASM data led to a clear correlation between efficiency in production and an index of human development; this result is shown and discussed. Based on the potential of SSM to attend to the mineral market needs, efficiency in productivity is finally proposed as the main path to turn an ASM unit into a sustainable and profitable Small-Scale industrial extractive unit.

New approach for reduction of diesel consumption by comparing different mining haulage configurations.

The mining operations of loading and haulage have an energy source that is highly dependent on fossil fuels. In mining companies that select trucks for haulage, this input is the main component of mining costs. How can the impact of the operational aspects on the diesel consumption of haulage operations in surface mines be assessed? There are many studies relating the consumption of fuel trucks to several variables, but a methodology that prioritizes higher-impact variables under each specific condition is not available. Generic models may not apply to all operational settings presented in the mining industry. This study aims to create a method of analysis, identification, and prioritization of variables related to fuel consumption of haul trucks in open pit mines. For this purpose, statistical analysis techniques and mathematical modelling tools using multiple linear regressions will be applied. The model is shown to be suitable because the results generate a good description of the fuel consumption behaviour. In the practical application of the method, the reduction of diesel consumption reached 10%. The implementation requires no large-scale investments or very long deadlines and can be applied to mining haulage operations in other settings.

Technical and operational aspects of tunnel rounds in artisanal underground mining

In the world today, due to the current high price of gold, thousands of artisanal small-scale mines operate without the financial or technical capacity to upgrade their production methods, often using equipment and working methods that were forsaken decades ago in the conventional mining industry. This article illustrates, with a practical example, that it is possible to achieve the modern requirements of quality, safety and productivity, while operating with mining equipment that basically possesses the same characteristics as that employed in the 1950s. The operation involved the excavation of a 6 meter long tunnel and over 25 stoping sections in both rock and concrete by drilling and blasting in an underground gold mine. The article describes how the main operational problems were overcome. An effective drilling pattern was designed in order to be easily achievable with the limited local equipment. The behavior of the local nitrate explosive was effectively predicted and managed. The interaction with the drilling teams was managed in order to determine a meeting point between their traditional working methods and the scientific view of the engineer. At the end of the article some general guidelines are proposed for the management of similar situations, in order to improve the efficiency, productivity and safety of drill and blast operations in small-scale mines.

Risk Management Incorporated to Life-of-Mine Planning at Sossego Copper Mine, Carajás, Brazil

Open pit mine design and production scheduling deals with the quest for most profitable mining sequence over the life of a mine. The dynamics of mining ore and waste, and spatial grade uncertainty make predictions of the optimal mining sequence a challenging task. Valuation and related decision-making in surface mining require the assessment and management of orebody risk in the generation of a pit design and long term production scheduling. As the most profitable mining sequence over de life of a mine determines both economic outcome of a project and the technical plan to be followed from mine development to mine closure, the adverse effects of orebody risk on performance is critical and are documented in various studies. Ignoring such a consequential source of risk and uncertainty may lead to unrealistic production plans. This paper presented a set of procedures that enable mine planning engineers to carry out a series of analysis, which can be used to evaluate the sensitivity of incremental pit shells and pit designs to grade uncertainty. The results obtained from the analysis have shown to provide valuable information, which can be used to develop mining strategies that are risk resilient in relation to grade uncertainty. A real life application at Sossego copper mine ensure that such procedures are technically implementable, supporting decision-making as (a) in-fill drilling programs; (b) review of mining sequence; (c) identification of areas of upside potential and downside risk and (d) ore blending between mining areas in order to minimize the impact of high risk areas. The goal of this work is to provide an approach for clear risk analysis and management in mine planning cycle to various aspects of pit optimisation and design, resulting in more technically and economically sustainable life-of-mine production plans and mineral reserve depletion.

The mine value chain integration beyond the ERP systems

Enterprise Resource Planning (ERP) systems have now been widely implemented in several industries. The authors discuss their merits and pitfalls, explaining the reasons ERP systems fall short in the integration of the mine value chain and proposing a methodology to overcome their deficiencies. One key differentiation aspect of the mineral industry, is the uncertainty about ore quality until it is actually mined, which sets this whole industry apart from the rest of the manufacturing sector in terms of resource planning needs and control. This paper identifies the difficulties that standard ERP systems have in integrating the mine value chain through an exploratory study that includes a case study methodology denoting how ERP systems manage the functional areas of the mining industry, and how they fit into the mineral value chain Information Technology (IT) requirements. It also proposes a new concept that will allow to properly integrating the mine value chain beyond the ERP systems functionality, through the proper application of IT.

Application challenges for information and automation technologies in an underground mine in Brazil

Abstract Organizations can establish a value-added sustainable strategy by increasing as-set utilization. WLAN infrastructure in underground mines tends to be a consistent platform for reliability in data/information management, and assertive governance practices. It enables remote monitoring, registering and data transfer from a control room, avoiding unnecessary human exposure in risk zones while adding agility to op -eration and maintenance related processes. A series of challenges must be considered so that onboard electronic systems combined with information technology infrastructure can become part of the operational strategy. Leaders must effectively manage to adapt organizations to new standards. This study aims to discuss the challenges related to implement information and automation technologies in an underground mine in Bra-zil. Data collected in a base metals underground mine is the basis for utilization, reli-ability and productivity analysis of computerized drilling equipment operating under severe conditions. The study concludes that searching for state-of-the-art operational practices demands a cultural change in organizations, followed by a redefinition of peoples’ roles and processes, so technology can provide full integration and be used as a management platform for decision-making.

Mathematical model and supporting algorithm to aid the sequencing and scheduling of mining with loading equipment allocation

This paper focuses on the sequencing and scheduling problem of open pit mining, with the allocation of loading equipment considering a medium-term horizon. This study considers the existence of a heterogeneous loading equipment fleet and two types of mineable material, namely ore or waste rock. For the mining of ore, the following requirements are taken under consideration: the mixture quality, a crusher, the processing plant capacity and a stockpile, called ROM stockpile. In this context, we present a mathematical model in mixed integer linear programming, supported by an algorithm that is responsible for moving the time horizon at each model run, aiming to generate mining orders resolved with optimality. Together, these orders describe the loading equipment mining plan.

An Innovative Approach to Mine Blast Fragmentation Management Using Complexity Analysis: Three Case Studies

This paper introduces an innovative solution for devising a robust blasting plan that will present consistently good fragmentation performance under highly uncertain environments. The analysis will be carried out using complexity analysis tools, a model-free approach to complex systems which is particularly well suited to the problem of finding non-deterministic dependencies between multiple variables. The study is backed-up by data from over 2,000 blast records from Brazilian mines and identifies what are the critical aspects of the system and how to manage the blasting plan to reduce their impact on its performance.