Oscar Restrepo

• Professor (Full) at National University of Colombia

Driven by the rising demand for raw materials and the need for greater social acceptance, the mining industry is rapidly adapting to modern requirements. Academia is aware of these challenges and is addressing them by updating curricula, enhancing teaching practices, incorporating e-learning, and improving industry-academia and inter-university col...

Calcium sulphoaluminate (CSA) cements have proven to be a viable alternative to ordinary Portland cement (OPC) due to their advantageous attributes such as reduced CO 2 emissions and lower energy requirements during their production. These qualities contribute to ongoing efforts to advance sustainable practices and materials in the construction ind...

El proyecto titulado "Investigación aplicada con enfoque territorial para el proyecto de formación integral del cuerpo estudiantil de la Universidad Nacional de Colombia, sede Medellín, en ingeniería para la vida y el entorno", dirigido por el vicedecano de investigación y extensión de la Facultad de Minas, profesor Oscar Jaime Restrepo y el auxili...

El mundo como lo conocemos está cambiando. Y no solo en lo relacionado con la ciencia o la tecnología. En áreas como la educación, por ejemplo, los expertos se atreven a anticipar que en menos de una década los sistemas de enseñanza dejarán de ser como los conocemos: aparecerá una nueva forma de ser maestro y de ser alumno. El futuro estará en mano...

According to the International Energy Agency, clean energy transitions significantly increase strategic minerals demand [...]

En este artículo se pretende realizar un diagnóstico sobre la situación actual del cierre de las minas en Colombia, transferir el conocimiento y experiencia vivida por Alemania por los autores en ese aspecto, identificar la normatividad que se ha establecido en el país hasta la actualidad con respecto a cierre minero, los desafíos que enfrenta el p...

A meaning of sustainability in the mining industry might be approached from the transformations that happen in territories where mining developments occur. This paper proposes a conceptual model that illustrates an alternative approach to interpret sustainability in a territory intervened by mining projects integrating the relationships and transfo...

Despite the importance that industrial activities have to society, for some years certain corporative sectors, such as mining, have faced strong criticism from various circles of global public opinion. This has hampered important industrial projects, generating great economic losses for companies and regions. While some localized studies indicate t...

This article aims to make a diagnosis of the current situation of mine closure in Colombia, to transfer the knowledge and experience lived by Germany in this aspect, to identify the regulations that have been established in the country to date concerning to mine closure, the challenges faced by the country, the initiatives and possible solutions th...

This paper presents the results obtained by processing a gold and silver telluride mineral concentrate from a mine in Colombia. An acid wash, also known as acidification, was carried out, followed by oxidation with nitric acid as a pretreatment. Cyanidations of the pretreatment residues were carried out and the results were compared with results fr...

En la educación ingenieril en los Estados Unidos y en la mayoría de los países del mundo, ha existido una separación histórica e ideológica entre el aprendizaje "social" y el "técnico", a pesar de que la práctica de la ingeniería siempre es sociotécnica. La mayoría de los planes de estudio de ingeniería se enfocan en temas técnicos, cubriendo super...

The greatest challenges for contemporary and future natural resource production are sociotechnical by nature, from public perceptions of mining to responsible mineral supply chains. The term sociotechnical signals that engineered systems have inherent social dimensions that require careful analysis. Sociotechnical thinking is a prerequisite for und...

Front-end stakeholder needs analysis is increasingly recognized as an essential component of sustainable engineering projects, yet most engineering curricula only cover this topic superficially. Fields like humanitarian engineering have long recognized the importance of stakeholder needs analysis for the success of development interventions, and re...

The synthesis of highly reactive dicalcium silicate phases by the alternative method flame spray pyrolysis (FSP) was investigated. Five main conditions of the synthesis process were varied and analyzed by applying a two-level fractional factorial design 2 5-2 resolution III, with a replica of a chemical system defined by a mixture of Ca (O 2 CCH 2...

Different coexistence models of artisanal gold miners with conventional mining companies of any size in Latin America are presented. The existing models herein assessed leave the mining activities with artisanal miners and processing steps are conducted by organized companies. These models, applied by various companies, is a solution to formalizing...

Fine waste management from quarry has been commonly the final disposal in mining tailings and as refilling material for landscape recovery in areas already exploited. However, different uses of these wastes have been studied, highlighting the earth constructions because a new economic benefit is generated and the environmental impact is reduced. Mo...

Informal recycling of electrical and electronic waste is a significant source of income for some families in the Global South. When workers implement unsafe practices, they are potentially exposed to hazardous chemicals that can negatively impact the environment and their health. Although this is a problem that has been studied for years, technolog...

The main contribution of this research is the study of the effect of the thermal inertia in the activation energy in calcium aluminate cement pastes. For this, several formulations of calcium aluminate cements paste with 51wt% and 71wt% of Al 2 O 3 were made at 0.4 water to cement ratios, and with additions of 0.0wt% and 20wt% of silica contents. T...

In this study, research on the use of monosodium glutamate for copper leaching, with emphasis on the thermodynamics and oxidant characteristics, is presented. Copper dissolution was conducted following a hydrometallurgical route, using monosodium glutamate in alkaline solutions. The effect of oxidizing agents such as hydrogen peroxide (H2O2) and po...

The concept of sustainability has been implicitly present in different historical milestones, mainly through economic thought, which expressed its concerns regarding the availability of resources, their use and distribution, understood at every moment by economic thinkers.

In this research, the effects of calcination and conventional milling, individually and as a combination of pre-treatments, on the pozzolanic activity of natural zeolites were analyzed and evaluated. The characterization of the material was done by techniques such as fluorescence and X-ray diffraction, thermogravimetric analysis, particle sizes dis...

Colombia has a great potential in natural resources where gold is one of the main protagonists of that potential. In recent decades, this precious metal has played an important and fundamental role in the social and economic dynamics of regions such as Antioquia, Chocó, Bolívar and Valle del Cauca, among others. This shows that gold mining can play...

Technical advancements in mine tailings recycling have led to the production of construction products such as bricks, cement, road pavers, and mortars in artisanal and small-scale mining (ASM) communities. Although such efforts show promise, the environmental, health, and social implications of such practices are often overlooked by stakeholders in...

Currently, the generation of electrical and electronic wastes is growing fast, thereby the reduction of the environmental impacts generated by its inadequate disposal is an ongoing challenge. In this study, a research on the use of monosodium glutamate for copper leaching, with emphasis on the thermodynamics and oxidant characteristics, is presente...

La colaboración internacional en proyectos humanitarios es cada vez más una parte importante de la educación de los ingenieros en su formación básica de pregrado, en especial cuando se trata de involucrar y retener a las mujeres en los programas de ingeniería. Sin embargo, estos proyectos frecuentemente están restringidos por limitaciones presupues...

Environmental remediation of polluted sites in developing communities often faces difficulties due to the misalignment of project objectives with the needs and interests of local communities, establishment of unrealistic expectations for the outcome of the project, and failure to account for the available resources in the community itself. Remediat...

The aim of this work is to explain the concepts of sustainability with respect to small artisanal gold mining. For this, a qualitative approach with a descriptive scope was used, for which the bibliographic review technique was conducted. In this sense, articles, theses, books and institutional documents, and any contribution related to the researc...

The substitution of the normalized aggregate by residual foundry sand (WFS) was studied on the physical properties of mortars by means of resistance to compression and capillary absorption tests. The aggregate was replaced by WFS in its natural state (WFS), washed residual foundry sand (WFSW) and heat treated residual foundry sand (WFST). The WFS h...

This paper is focused on working under the line of sustainability in small-scale informal gold mining projects, specifically in Colombia. It is interesting to study Artisanal and Small-Scale Mining (ASM) in Colombia from a business perspective as an activity that generates economic and sustainable development. ASM has great challenges to overcome i...

RESUMO Pirólisis de aerosol en llama (FSP), es una de las metodologías más prometedoras en la producción de nanopartículas a gran escala, dado su potencial de escalamiento y producción en continuo. Este artículo aborda los fenómenos químicos y físicos ocurridos durante el proceso, desde la preparación de la solución de precursores, los procesos de...

Este artículo se enfoca en trabajar bajo la línea de la sostenibilidad en proyectos de minería informal de oro a pequeña escala, específicamente en Colombia. Resulta interesante estudiar en Colombia la Minería Artesanal y a Pequeña Escala (MAPE) desde una perspectiva empresarial como actividad generadora de desarrollo económico y sostenible. La MAP...

Artisanal and small-scale gold mining (ASGM) continues to expand rapidly due to the increasing global price of gold and the economic impacts of COVID-19. This expansion of ASGM has raised concerns about mercury use and increased the number of projects designed to reduce or eliminate the use of mercury in ASGM in many developing countries. Unfortuna...

The production of highly reactive belite is of great interest since the possibility to produce cementitious materials with less demand of calcium oxide and energy. Belite cement clinkers were produced by the alternative process flame spray pyrolysis under oxidant environment using the metallic precursors calcium nitrate, calcium 2-ethylhexanoate an...

Several artisanal and small-scale gold mining (ASGM) sites in Colombia were located and sampled. At each ASGM site, tailings samples were collected and analyzed. Establishing rapport with mining stakeholders and analyzing the samples allowed our team to draw conclusions about the inefficiency of mercury-use in gold extraction and the superior effic...

This work studies the effect of nanosilica (NS) on the rheology of cement paste by comparing it with two high specific surface area silicas: silica fume (SF) and pyrogenic silica (PS). Portland cement pastes were produced with different water-to-cementing material ratios and different solid substitutions of cement by silica. Water demand, setting t...

The reuse and reincorporation of waste generated in the production processes are becoming increasingly important in the world, due to the double effect that it has in terms of sustainability. The first one is the environmental factor, since the impact generated is reduced by reducing the amount of wastes. The second one is the financial factor, sin...

This paper identifies the intersecting technical and social factors that have fueled a history of conflict between artisanal and small-scale mining (ASM) and large-scale mining, and more recently, their potential coexistence, in Marmato, Colombia. At Marmato, a vertically zoned ore body and corresponding vertically stacked land claims have in part...

The effect of a thermal pretreatment on the kinetic parameters and rate-controlling step for nickel leaching dissolution in hydrochloric acid‑sodium chloride solutions from a low – grade Colombian nickel laterite (1.15% Ni, 0.12% Co and 41.1% Fe), was evaluated. The mineralogical analysis showed that nickel is associated with iron in the form of he...

El cemento es de los materiales de mayor demanda a nivel mundial, con una producción de 4.000 millones de toneladas anuales. Su fabricación es responsable del ~8 % de las emisiones de CO2 globales, por lo cual plantean estrategias de mitigación del impacto ambiental ligadas a mejorar su proceso de producción. Los métodos alternativos usados hasta a...

The aim of this work is to find the effect of the cation M (Zn2+, Co2+, Cu2+, and Mg2+) on the optical properties of MFe2(P2O7)2 synthesized by solution combustion. The crystal structure of the powders was determined by X-ray diffraction (XRD), Infrared spectroscopy (IR), and Raman spectroscopy. The presence of Fe2+ and Fe3+ ions in the pigments wa...

The application of phosphonium-based ionic liquids (ILs) on the selective extraction of cobalt is presented. The extraction mechanism is established, and different parameters of the process are evaluated. It has been found that it is possible to extract cobalt from aqueous solutions in sulfate media, with the addition of sodium chloride, using phos...

Using a creative capacity building (CCB) framework, co-design workshops among artisanal and small-scale gold miners, government officials, NGO representatives, and academics can provide an effective mechanism to identify pressing needs and desires of miners and operators towards formalization. As recently implemented in Peru, one of these workshops...

Tricalcium silicate phases were synthesized by Flame Spray Pyrolysis with a subsequent thermal treatments, in order to achieve the desire phase. The mineralogical composition was obtain by XRD and the FTIR and Raman spectroscopy.

Celite was prepared by the alternative method of flame spray pyrolysis using as starting materials calcium nitrate and aluminum nitrate dissolved in ethanol. The sample was characterized by XRD, FT-IR, BET surface area analysis and microcalorimetry. The results show the formation of C3A cubic with a specific surface area of 3.92 m2/g. Keywords: S...

Calcium silicates production by alternative methods to the traditional solid state reaction method has gaining importance because of the possibility to obtain materials with higher performance than the traditional process. C3S and C2S phases play an important role in cement since they are responsible of the development of mechanical properties such...

C 3 S and C 2 S nanoparticles were synthesized by the novel alternative method Flame Spray Pyrolysis, allowing a continuous production process. To obtain the crystalline phases was necessary to calcine the samples at 1000°C and 1400°C during 2 hours. The products were analyzed by XRD, FT-IR and SEM.

In this research, inorganic pigment with spinel structure CoCr2O4 was synthesized by the solution combustion synthesis using glycine as fuel in a one-step. The powders as-prepared after combustion and then calcined at 700°C during 6 hours, were characterized by the X-ray diffraction (XRD), and both samples showed the peaks corresponding to the expe...

The Portland cement clinker consists of 95% calcium oxide, silicon, aluminium and iron and 5% impurities of magnesium, sodium, potassium, titanium, sulfur, phosphorus and manganese. From the combination of two or more of the main oxides, the constituents of the white clinker are formed, corresponding to alite(3CaO.SiO2 or C3S), belite (2CaO.SiO2 or...

Calcium silicate phases were synthesized by Flame Spray Pyrolysis, in order to evaluate the effects of the process conditions over the mineralogy and specific surface area of the samples. The mineralogical composition was obtain by Rietveld refinement of XRD patterns and the specific surface area by BET. Keywords: Synthesis, Flame Spray Pyrolysis...

This study provides data on the occurrence and distribution of rare earth elements, yttrium, and scandium (REY + Sc) in coals and non-coal lithologies associated with coals from various Colombian coalfields. A number of authors have characterized the REY + Sc content of various international coal deposits; however, no study to date has specifically...

Cyanide is one of the most used reagents in the precious metal extraction process; as well as the most efficient from the point of view of the dissolution process, but it is also a toxic product that requires a lot of care in handling. Likewise, the residual solutions of the process must be followed because they can be a risk of contamination of wa...

Los pigmentos inorgánicos azules con estructura espinela CoAl1.95Cr0.05O4 y Zn0,8Co0,2Al2O4 se sintetizaron por el método de síntesis de combustión en solución usando glicina como combustible. La estructura cristalina de los polvos sintetizados fue determinada por el método de difracción de rayos X (DRX), el cual mostró la formación de la estructur...

In this work, the effect of pyrogenic silica and nanosilica on the properties of portland cement matrices is compared. Two chemically and mineralogically similar mineral additions (amorphous silica) with different particle size and specific surface area were used to prepare pastes and mortars with different solids substitutions of cement by silica....

Synthesis of dicalcium silicate (2CaO.SiO2 or C2S) through flame spray pyrolysis and a solution combustion method was investigated by the variation of flames and fuels. The synthesized powders were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM). X-ray diffraction analysis revealed...

Lateritic nickel ores need to be reduced to obtain direct reduced iron and nickel alloy. During processing of lateritic nickel ores in rotary kilns, there is a great loss of fines of ores due to degradation during transport into the reactor. These fines contain substantial amounts of nickel and iron, which could be recovered if they are agglomerate...

Cyanide leaching is the predominant process of gold extraction in large scale mining. Current initiatives for reducing the use of mercury in small scale and artisanal mining tend towards the cyanide technology as the only feasible alternative. Thus, the deliberate handling in consideration of the hazardous nature of cyanide compounds is an issue of...

Calcium silicates production by alternative methods to solid state reaction method has gained importance because of the possibility to obtain materials with higher performance and less energy consumption than the traditional process. Exploring the application of non-conventional methods for the production of cementitious materials is an interesting...

In this paper, Mg0.5Ti2(PO4)3 with the NASICON-type structure was evaluated for the first time as a possible host structure of Co²⁺ for obtaining an inorganic pigment with violet color. The powders were synthesized by solution combustion synthesis using glycine (G) and urea (U) as fuels and different oxidizer-to-fuel (O/F) ratios when ammonium nitr...

Developing its large-scale mining industry is an economic priority for Colombia. However, national capacity to assess and manage the water resource impacts of mining is currently limited. This includes lack of baseline data, lack of suitable hydrological models and lack of frameworks for evaluating risks. Furthermore, public opposition to large sca...

New and extraordinary physical-chemical properties of materials at nanoscale open up new applications for the building and infrastructure industry such as structural reinforcements, electronic properties and energy harvesting. Therefore the issues and risks associated with the manufacturing of nanomaterials are now of big concern due to the large v...

Resumen La inclusión de planes efectivos de cierre de mina en el proyecto de explotación es la vía para compensar el efecto nocivo de esta actividad. A partir de un diagnóstico realizado en 11 yacimientos en explotación, pertenecientes a la empresa Canteras, se diseñó una metodología con un enfoque sistémico e integral que consta de cinco etapas q...

The inclusion of effective mine closure plans in the exploitation project is the way to compensate for the harmful effect of this activity. Based on a diagnosis carried out in 11 sites in operation, belonging to the company Canteras, a methodology was designed with a systemic and integral approach that consists of three stages and allows the execut...

Flame spray pyrolysis (FSP) is a bottom-up process used to generate nanopowders with precise compositional control, where the processing conditions have an strong impact over the products properties. Therefore, the process conditions variations need to be study for each solvent-precursors system.

This research was conducted with the purpose of creating a method of recycling of e-waste, based on the contact pins of computers for the extraction of copper, with the aim of reducing the environmental impacts generated by the inadequate disposal of these wastes, which due to the constant technological advances are growing dramatically. The dissol...

The green ceramic pigments CoCr 2 O 4 were successfully produced by flame spray pyrolysis and solid state reaction methods, obtaining products with high purity and crystallinity without a subsequent calcination. The particles presented a broad size distribution between nano and micro sizes (10 nm-1 µm) and strong agglomerations, with the presence o...

Always, as a professor of Mining Engineering, I have believed in the great potential that man has to develop all his creative potential and that the most appropriate means for this is the incessant search for knowledge through teaching. I believe that knowledge is a search for unity between the individual and objects through human intelligence.

Spinel structure CoCr2O4 was synthesized by the non-conventional method flame spray pyrolysis (FSP) and the traditional route solid state reaction, where the optical properties were evaluated. The influences of FSP conditions as pressure of dispersion air and ceramic load of the solution over optical properties were evaluated using a 22 full factor...

In this research both the microstructure and thickness of the interfacial transition zone (ITZ) in concretes of Portland cement and lightweight aggregates (LWA) are studied. It has been established that the microstructure in the ITZ strongly depends on the nature of the aggregate, specifically its porosity and water absorption. This study aims at r...

Mining represents an important economic sector in almost all countries, especially the developing ones. The planning in this area is complex due to the interaction between different aspects like economic factors, environmental and social issues, and government regulation. A tool for policy analysis is needed to understand and test the effects of ne...

In this research both the microstructure and thickness of the interfacial transition zone (ITZ) in concretes of Portland cement and lightweight aggregates (LWA) are studied. It has been established that the microstructure in the ITZ strongly depends on the nature of the aggregate, specifically its porosity and water absorption. This study aims at r...

Sodium cyanide reagent has been chosen for the leaching of gold for over 100 years due to their high recoveries of gold and relatively low costs. Environmental damage from misuse of it has encouraged the search for alternatives to recover gold efficiently and environmentally friendly. This article aims to study the mass balance, concentration gradi...