Giorgio de Tomi’s research while affiliated with University of São Paulo and other places

Some open-pit mining operations rely heavily on stockyards as temporary storage areas. In addition to its conventional purpose, it is regarded as an excellent way for blending deposited material, which reduces fluctuation in the grade of material provided to the processing plant. However, traceability of the grade of material in the stockyard poses considerable issues due to the necessity for more specific information about the stored material. This study aims to create a block model for the stockyard using programming based on an integrated database, incorporating critical information from fleet management systems, geology, and topography. The model is generated in a widely compatible format that can be imported into any planning software for further analysis. Geostatistical estimation was excluded from this investigation due to the uneven distribution of mineral grades and the low precision of truck GPS. Subsequently, short-term planning for stockyard reclaiming is carried out using block modeling, primarily satisfying the beneficiation plant's production demands. Results showed 100% adherence to permissible limits of plant feed grade compared to 33% in the absence of incorporating variables. Properly integrating these components aims to improve operational efficiency and the quality of material input to the processing plant, aiding mining engineers in managing the stockyard and developing more robust short-term plans.

O artigo analisa a influência do teor de corte na análise da viabilidade de um projeto de mineração de cobre e como essas flutuações impactam os indicadores econômicos de projetos de mineração com baixo teor. Inicialmente, o preço de venda base foi estabelecido em 7,7 US$/t, com incrementos em intervalos de 10$ -30,4 M, indicando inviabilidade econômica nesse cenário. Por outro lado, a cava com revenue factor de 150% exibe um VPL positivo de US$66,6 M, resultando em uma diferença de US$ 97,2 M entre os dois extremos. Além disso, ao comparar a cava de 100%, que representa o cenário base, com a de 150%, observa-se uma variação de US$ 64 M, evidenciando o impacto da ampliação da cava na rentabilidade do projeto. Conclui-se que a compreensão detalhada do teor de corte e das flutuações nos preços é essencial para embasar decisões estratégicas e operacionais, visando à otimização do desempenho financeiro dos projetos de mineração.

The selection of an underground mining method stems from a multivariate analysis that considers geomechanical, geological, economic, and operational parameters. Even after identifying the most compatible method, there is no assurance that the mining company will achieve the best performance. The geological complexity of some deposits requires adaptations of methods described in the literature to obtain more selectivity and reduce mining waste. There are some studies on geometry of underground structures, but a methodology that describes an adaptation of a room-and-pillar mining method for ore bodies with down-dip varying from 20° to 25° is novel. The present work aimed to reduce dilution by adapting the traditional room-and-pillar mining method (TRP) to inclined ore bodies. This new method is entitled short-hole room-and-pillar (SHRP). The equations that measure the dilution are defined according to the geometry of stopes and openings. The results comprise comparative analyses of the operational and planned dilutions to measure the performance of the SHRP method. The average operating dilution of the SHRP method was more than five times lower than the planned dilution according to the TRP method. Low operational dilution indicates high selectivity of the method and its potential to reduce underground mining tailings.

The study examines productive and unproductive hours in four underground mine shifts: 6 h, 8 h, 10 h, and 12 h. Moreover, two sub-scenarios of single or two blasts examined the effect on mine utilization regarding effective working hours in underground mines. Cuiabá Mine data, the Brazilian’s largest and deepest underground gold mine, was used in both sub-scenarios. Under the first sub-scenario, which assumes two blasts per day, the 6-h shift had an effective work time (EWT) of 13 h and 30 min or 56.3% of the day. The EWT was 15 h and 20 min, 63.9% of the day, in the 8-h shift scenario. The 15-h, 30-min EWT took 64.6% of the day in both 10/12-h shifts. The 6-h scenario had an EWT of 16 h and 15 min (67.7%) in the second sub-scenario with a single blast daily. The 8-h scenario boosted EWT to 18 h and 25 min (76.7%) daily. An EWT of 18 h and 35 min daily (77.4%) was found in 10/12-h shifts. Comparisons of both sub-scenarios show that EWT positively correlates with shift length. Sub-scenario 1 has a 7.6% incremental step from 6 to 8 h, while sub-scenario 2 has 9%. EWT increases from 8-h to 10/12-h shifts by 0.7% for single and two blasts daily. Compared to the two sub-scenarios, halting operations for blasting once daily improves the EWT average by 12.5%. Reducing blasting and changing underground mining shift duration might boost economic viability.

Adequate and clean water supplies play a huge role in human health and wellness. Therefore, the causes of contamination and pollution of water supplies must be addressed. Mining activities are often considered a threat to surface water bodies due to the huge amount of water involved in their processes and the attendant pollution, which may result in conflicts between the mining communities and company involved. In this research, the social license to operate was proposed as a tool to negotiate and mitigate these conflicts. Some oil sand communities in Nigeria were used as a case study. Reconnaissance survey and a semi-structured interview within the study area were deployed to document the expected impact of the deposit exploration on freshwater in the area. In addition, a comparative literature study to evaluate the use of social license to operate in a similar situation was considered. Our scenario simulations suggest that oil sand mining activities could negatively impact the environment during the three phases of mining activities and if these effects are not proactivity resolved, it may lead to conflicts with host communities. It was proposed that the mining company should secure a social license to operate from the community before carrying out their activities in order to reduce delays and conflicts. The community will grant an informal license to the company. This social license to operate will serve as a tool for communication and negotiations between the two parties where agreements can be reached.

Cement sheath integrity is a critical concern in the successful implementation of geologic carbon capture and storage (CCS) projects. Conventional ordinary Portland cement (OPC) is not thermodynamically compatible with the carbon dioxide (CO 2 ) present in CO 2 storage media. When OPC cement sheaths interact with aqueous CO 2 , they undergo degradation, producing calcium bicarbonate. This bicarbonate readily dissolves in the formation aquifer and can create leakage pathways, compromising the integrity of the wellbores. This study comprehensively reviews the state-of-the-art techniques for evaluating cement sheath integrity, providing a comprehensive compendium of available methods in a single article. The paper’s objective is to support the deployment of successful CCS projects, facilitate the remediation of affected wellbores in CO 2 storage systems, and offer guidelines for evaluating improved cement slurry designs and formulations. Additionally, the study identifies the factors that influence cement sheath integrity when exposed to aqueous CO 2 , including in-situ temperature and pressure, reservoir fluid characteristics, cement slurry formulations, and wellbore operations. Furthermore, various modes of mechanical failure in cement sheaths are identified, such as radial cracking, plastic deformation, inner and outer debonding, and channeling. Understanding these failure mechanisms is crucial for designing robust cementing strategies in CCS applications. Evaluation techniques for assessing the integrity of cement sheaths exposed to aqueous CO 2 encompass a range of approaches. These include direct experimentation with samples that mimic the in -situ conditions of storage sites, well logging for monitoring leakages, analytical, numerical, and statistical modeling, and risk assessments. Direct experimentation plays a vital role in understanding the carbonation kinetics and changes in cement sheaths' mechanical and transport properties. Techniques such as scanning electron microscopy, back-scattered electron image detectors, energy-dispersive spectroscopy, mercury intrusion porosimetry, optical microscopy, X-ray diffraction, electrical resistivity imaging, electron probe microanalyzers, inductivity-coupled plasma optical emission spectrometry, X-ray computed microtomography, Raman spectroscopy, direct image correlation, and particle velocimetry are utilized for direct experimentation. Analytical and numerical modeling approaches include reactive transport modeling, multi-scale modeling, computational fluid dynamics (CFD), and artificial intelligence (AI)-based modeling. In field operations, the integrity of the cement sheaths can be evaluated using cement bond evaluation tools, pressure transient test tools, cement coring tools, or sustained casing pressure analysis. These techniques collectively enable a comprehensive assessment of the integrity of cement sheath exposed to aqueous CO 2 , aiding in optimizing and monitoring carbon storage systems. Every CO 2 storage medium is unique. Optimal assessment of the cement sheaths' integrity of its wellbore systems, when exposed to aqueous CO 2 , would require a different combination of suitable evaluation techniques. Future studies should focus on developing standardized guidelines that combine laboratory testing, field-scale testing, and numerical modeling to predict the evolution of cement sheath integrity when exposed to aqueous CO 2 . Additional research is necessary to determine the optimal combinations of cement additives that enhance long-term resilience and resistance to carbonic acid attacks, enabling successful geologic sequestration. Furthermore, there are ample research opportunities to advance numerical modeling techniques for evaluating the effects of aqueous CO 2 on cement sheath integrity and identifying potential failure mechanisms.

O ouro é um ativo amplamente comercializado e consumido em todo o mundo, com uma grande variedade de partes interessadas, incluindo o mercado financeiro, joalherias, engenharia biomédica e indústria eletrônica, entre outros. Além disso, o ouro tem um papel crítico na transição energética para tecnologias limpas programada para este século. Cada vez mais, nota-se uma tendência global de privilegiar a cadeia de valor de ouro produzido de forma responsável em todas as suas aplicações atuais e futuras.