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By J. H. E. Jeffes, C. Diaz

The heat balance and chemical equilibria involved in the production of blister copper from a chalcopyrite concentrate in a single operation are examined. It appears that two stages—one oxidising and one reducing—will be required. The analysis indicates that on thermal grounds the process is possible with a dry, high-grade chalcopyrite concentrate, if oxygen enrichment to about 30 per cent is used, but that copper losses in the slag will be serious and will require a secondary recovery operation. More extensive data on the activities of copper oxide in slags are required to elucidate this point more effectively

Dec 1, 1971

By M. J. O'Hara

El presente texto describe el programa "Apolo" dentro de la geología lunar. Dicho programa revisa los comienzos del sistema solar y estudia los desconocidos procesos de "erosión" y "evolución" de las rocas que han tenido lugar en la Luna. Asi también se describe el origen de la luna, procesos de superficie, las montañas lunares, formación de mares lunares, concentraciones de masa y el interior de la luna.

Nov 1, 1971

By S. H. Boshlov

Los problemas del diseño estructural de minas se basan en numerosas complejidades como el de una incapacidad para definir explícitamente los parámetros, físicos in situ del medio rocoso y sus materiales asociados, el comportamiento del sistema bajo alguna descripción bosquejada de la aplicación de la carga; otras proceden de la incapacidad para especificar con precisión el estado inicial de la tensión en el medio. En ese sentido, el presente texto señala un modelo de diseño estructural manipulable donde se refleje el comportamiento del prototipo que representa. Así, el análisis por elementos finitos, en el cual la estructura se considera como una reunión de numerosos elementos, cuyas propiedades individuales pueden señalarse a voluntad, indica la posibilidad de un problema de diseño de una estructura minera como un ejercicio de análisis de sistemas. Tal sistema rocoso podría incluir todos los factores naturales y los medios ambientes artificales que afectan la resistencia de las estructuras mineras de superficie interior.

Nov 1, 1971

By Jorgen Damgaard

El proceso de deshidratación de los minerales comprende espesamiento, filtración y secado y una operación típica. En ese sentido, el presente texto señala el secado por atomización donde se busca eliminar el agua de las pulpas espesas para producir concentrados de forma directa y así mostrar el impacto que este tiene en el manejo, permitiendo operaciones de sistemas de transportes integrados en recipientes a granel que van desde la mina a la fundición, a través de sistemas de transportes neumáticos totalmente cerrados.

Nov 1, 1971

By K. H. Hofer

La mecánica de rocas se basa en el descubrimiento de las leyes que siguen las perturbaciones del estado natural de la corteza terrestre provocadas por la actividad minera. En ese sentido, el presente texto señala la importancia de este proceso en la ciencia de la minería -en tanto revisa el comportamiento de la resistencia de la roca, determina el estado de las tensiones primarias de la corteza terrestre y analiza la repartición secundaria de tensiones provocadas por la formación de huecos y sus consecuencias sobre la roca en el espacio y tiempo.

Nov 1, 1971

This report describes the investigational work on the development of a fire-assay method capable of concentrating, in a button of nickel sulphide, all six of the platinum-group metals present in samples of ores, concentrates, and mattes. In the method adopted, the sample is fused with a mixture of sodium carbonate, sodium tetraborate, nickel carbonate, and sulphur. The nickel sulphide formed during fusion collects the noble metals and carries them to the bottom of the crucible. The nickel sulphide button is dissolved, and the noble metals are isolated and determined. The coefficients of variation range between 1,0 and 4,9 per cent for the various platinum-group metals when they are present in concentrations between 0,3 and 75 p.p.m.

Oct 15, 1971

By Vicente Gonzáles Otoya

El presente texto describe el descubrimiento, cubicación y evaluación del fosfato de Bu -Craa en la provincia de Sahara. Para ello, se realizó campañas donde se hizo el reconocimiento exhaustivo del límite de afloramiento del Paleoceno en toda la provincia, que va desde Hasi Melehes hasta Villa Cisneros, así como se determinó que las capas fosfatadas importantes estaban localizadas en este tramo geológico. Así también se revela la geografía, sondeos, testificaciones, pozos y calicatas y la organización del trabajo de evaluación de dicho sector.

Sep 1, 1971

By Mario A. Espinoza

"El presente texto señala la función del médico en la prevención de las enfermedades ocupacionales. La Salud Ocupacional, no solo concierne a la prevención de las enfermedades ocupacionales, debidas a la inhalaciónde ciertas sustancias químicas como el plomo, benzol, polvos de sílice u otras, sino que estudia los efectos fisiológicos del trabajo y ambiente físico y psicosocial del trabajador. En ese sentido, es importante la participación de profesionales en los programas de salud ocupacional como la del médico quien se encarga de aceptar a los postuiantes que física y mentalmente están capacitados para realizar trabajos sin ninguna limitación, clasificar a los postulantes que no demuestren aptitud para el trabajo que solicitan, asignándoles otras colocaciones y los proteje de los riesgos inherentes al trabajo a través de una distribución adecuada de sus funciones. "

Sep 1, 1971

By R. Duval

El presente texto señala el muestreo de lotes de mineral a granel a través de la selección de individuos que componen la población a muestrear, la selección de masas iguales, la selección de individuos con volúmenes iguales y la selección de individuos que se proyectan verticalmente sobre un plano horizontal, así como el muestreo de yacimientos (muestreo de métodos clásicos, el muestreo de individuos con volumen constante y de acumulación).

Jul 1, 1971

By L. M. Kaas

El presente artículo señala el uso de la computadora desde 1950 y sus avances a lo largo de la historia industrial y de producción. En este sentido, anteriormente ninguna fase de los procesos de minería y de molienda ha quedado sin investigar para encontrar nuevas aplicaciones de este aparato. Hoy, los problemas de geología, minería, preparación de minerales y gestion -muchos hasta hace tiempo imposibles de tratarse han resuelto satisfactoriamente con el empleo del computador.

Jul 1, 1971

By R. Duval

El presente texto se basa en la estadística clásica del muestreo que indica los lotes de materiales minerales al granel y de yacimientos mineros a los ingenieros. Este sistema describe las fallas que afectan los resultados de los muestreos cuando se emplea métodos, sin las debidas precauciones. Así también se muestran los tres principios esenciales que son la base del muestreo simple al azar, donde se funda toda la teoría estadistíca del muestreo

Jul 1, 1971

By José Claro

El presente texto señala algunos aspectos respecto al financiamiento de inversiones en la minería. Para ello, se revisa las condiciones adecuadas para la comercialización de su producto a través de tres premisas: La primera, refiere los préstamos otorgados por los gobiernos de países desarrollados y sus agencias financieras para nuevas producciones mineras; la segunda, considera los préstamos de futuros compradores como una fuente importante de financiamiento y la tercera, refiere a los bancos comerciales, cuyos préstamos permiten mayor agilidad en su utilización, aunque es cada vez más dificil encontrarlos a tipos de interés y plazos adecuados. Asimismo, otra modalidad frecuente en el caso de financiamiento, es que la misma empresa minera o sus accionistas intervengan en la capitalización de la nueva empresa minera a través de préstamos o cuasi capital, de forma que se recupere la inversión a través del pago de préstamos e intereses, en lugar de recibir las utilidades en forma de dividendos sujetos a impuestos.

Mar 1, 1971

By Jorge Vargas Fernández

El presente artículo describe la relación entre la cultura y los recursos mineros a través del tiempo y las acciones para mantener dicha relación, dada la importancia que tiene para el desarrollo y seguridad del Perú.

Mar 1, 1971

By Maurice Allais

El presente texto señala la importancia de la investigación en la formación económica del ingeniero donde el cálculo económico es la base de la enseñanza de las grandes escuelas. En este sentido, es importante conocer la teoría de los óptimos económicos, la teoría del rendimiento social o teoría de la eficiencia. Asimismo, debe mostrarse el significado del precio, los cálculos de rentabilidad, la teoría del riesgo (probabilidad) y las decisiones que incluyan elementos aleatorios.

Mar 1, 1971

By Robert Head

El presente texto señala las probables tendencias de la industria cuprífera a lo largo de esta década, donde los pronósticos de una parte se basan en los hechos y datos del pasado, tanto de producción como de consumo. En cuanto la producción futura, ésta se basa sobre disminuciones en minas cuyas reservas se agotan, incrementos de minas en plena vida y minas nuevas o probables que serán llevadas a la producción a través de la década. Como consecuencia de esta posición de adecuado abastecimiento la tendencia a investigar por materiales en sustitución del cobre puede ser reducida. Asimismo, la nueva de producción vendrá de minas más grandes, de baja ley que necesitarán grandes inversiones de capital.

Mar 1, 1971

By J. P. Coetzee

Dr. K. Gebhard In his excellent and comprehensive survey on the future development of the Iron and Steel Industry in South Africa, Mr. Coetzee has also mentioned the direct reduction processes as a possible method of converting iron ore to iron. Mr. Coetzee has made it quite clear that at this stage one should not consider these processes as a 'magic formula' which herald a 'break through'. I agree entirely with this point of view. Once upon a time I held the opposite view, but in the meantime I have revised my views. To do so, I had 40 years at my disposal. In 1930 I had the privilege of being connected with the first commercial sponge iron plant in Germany1 - a plant which was capable of producing 40 tons of sponge iron a day. We were determined to prove that the blast furnace would become obsolete in the near future. We considered it as an unnecessary detour to convert iron ore first into an iron-carbon alloy, which contained further quite a number of undesirable elements, and to remove this carbon by an endothermic process. Direct iron-making seemed to be a logical short cut. Unfortunately, we were not able to establish this 'short cut,', but the life of our sponge iron plant was cut short. We had solved all technical but not the economic problems. Basically the positon is still the same today - mainly economic and to a lesser degree technological aspects determine the rate at which sponge iron plants are installed. More has been said and written than done about direct reduction plants. I think that there are two main reasons for this stagnation in the introduction of direct reduction processes. The first reason is that modern blast furnaces are just too good and too economic ever to be replaced by direct reduction processes on a large scale. This, of course, already limits the field of application for direct reduction plants. The second reason is that sponge iron production and utilisation is based on technical considerations, which increase not only the production cost of sponge iron but also the conversion cost to steel to such an extent that under special conditions only are direct reduction plants an economic proposition. Are these technical considerations still as forceful and valid today as they were when 'direct steelmaking' was first contemplated? The development of sponge iron production as a method of direct

Jan 3, 1971

By Jonas Svensson

A new method is described for the production of cold-bonded pellets using a hydraulic binder, such as portland cement. Large-scale pilot-plant tests have proved that self-fluxing pellets of high reducibility and good handling strength can be made by the method. Blast-furnace trials have shown that the pellets are an acceptable burden material, comparable with self-fluxing sinter or heat-hardened pellets. Economic factors of commercial-scale production are discussed. The Grangcold Pellet Process—for which patents have been applied or already granted in a number of coun-tries—uses a hydraulic adhesive such as portland cement, slag cements, pozzolanic cements, etc., for the production of cold-bonded pellets. The idea of using a hydraulic binder for the agglomeration of iron-ore fines is not new. Portland cement was proposed as an adhesive for cold-bonded iron-ore briquettes in patents granted more than 50 years ago.' In a report on the briquetting of iron-ore fines, published in Stahl und Eisen in 1959; it is stated that briquettes bonded with portland cement are used on a small scale at an ironwork in Germany. According to the report, the briquettes showed excellent strength in the blast furnace although their general use was made impossible because they required a long hardening time, during which they are sticky, soft, and difficult to store and handle. The Grangcold Pellet Process has overcome this particular disadvantage by mixing the balls with a suitable amount of the balling concentrate before storing them. The pellets are embedded in the concentrated during storing in such a way that they are isolated from each other and thus prevented from sticking together to form clusters. Thanks to the embedding concentrate, the pellets are subjected to a more or less uniform pressure from all sides which does not deform them. Thus, the mixture can be stored in a stockpile or in a bin until the pellets have hardened sufficiently. The concentrate is separated from the pellets by means of screening. The concentrate is returned to the balling operation and the pellets are either shipped to the blast furnace or stored for final hardening. The binder preferred for the Grangcold Pellett Process is portland-cement clinker, ground without the admixture of gypsum in order to avoid sulfur in the pellets as far as possible. Usually a 10% binder content is used. Two-thirds of the portland-cement clinker consist of lime and the rest is silica, alumina, and ferric oxide. Thus, self-fluxing or overbasic pellets are produced with this binder if the amount of silica in the concentrate used does not exceed 4%. The Grangcold Pellet Process was developed by the mineral Processing Laboratory of the Granges Co. Work started in 1963 with batch-scale tests. In 1966, a small pilot plant was put into operation in which 1800 tons of pellets were produced using 10% of rapid-hardening portland cement as a binder. Favorable results from a blast-furnace test with this batch led to the decision to erect a larger pilot plant which went into production in the summer of 1967. Since then, approximately 100,000 tons of cold-bonded pellets have been produced, mostly with 10% gypsum-free portland cement as a binder. Several full-scale blast-furnace trials have been performed with the pellets. The results of the trials indicate that the Grangcold pellets constitute a satisfactory blast-furnace feed. An industrial plant for the production of Grangcold pellets with a rated capacity of 1.5 million tpy is now under construction at the Granges Co.'s mine at Grangesberg. The plant will come into operation in the summer of 1970. Results from Laboratory Work Pellets made from iron-ore concentrate bonded with portland cement harden slowly and their handling is very critical until they have hardened enough to loose their stickiness. It is therefore especially important to study the progress of the hardening action and the factors influencing it. This is best achieved by investigating the relationship between the compressive strength of the cement-bonded pellets and the curing time under varied conditions. The general course of this relation-

Jan 1, 1971

By Richard N. Spencer

This report describes investigations of the economic merits of multiple zone mining and beneficiation versus selective mining of altered Western phosphate rock. The same deposit was considered in both instances and it was assumed that the grade of selectively mined ore was comparable to the grade of the concentrate from beneficiation. The beneficiating scheme used for the investigation was one proved by small continuous circuit operation. All economic factors were found to favor multiple zone mining plus beneficiation. Capital requirements and production costs were lower, and production life of the deposit was extended 4.5 times. The concentrate from beneficiation would be a uniform high-quality feed for acidulation and would be low in stable metallic oxide (R203) content. Such a feed would permit improved plant operating control, and the low R203 would promote more rapid filtration and minimize sludge formation in the phosphoric acid. With the proposed treatment, the concentrate produced by flotation from this deposit would cost about 1.5 times as much per ton as the concentrate produced by classification sizing. Therefore, inclusion of a flotation step in treatment schemes requires an economic analysis for each ore deposit.

Jan 1, 1971

By Thomas J. Wright

The evaluation and development of the Eastern North Carolina phosphate deposit resulted in one of the world's largest and most modern phosphate mines and fertilizer complexes at an investment in excess of $90,000,000. The resulting ore beneficiation process showed excellent correlation with pilot plant data. A number of variations from current industrial practices were introduced and projected from bench scale tests through pilot plant to production. Principal among these variations were the following: 1) removal of magnesium by classification, 2) simultaneous flotation of coarse and fine phosphate, 3) the use of saponified fatty acid, 4) utilization of filter wash water for deoiling, 5) utilization of a rougher concentrate for acidulation, 6) calcination of flotation concentrates, and 7) elimination of grinding prior to the manufacture of phosphoric acid.

Jan 1, 1971

By Walter H. Ortel, George B. Wallace

INTRODUCTION A greater understanding is required about the factors which control tunneling operations if we are to meet the expected demand for tunnels. Much of the needed information can best be achieved by the proper use of instrumentation and advanced engineering concepts. Tunnel measurements and their analysis may prove to be the key which will give the insight necessary to understand the relationship of rock, tunnel supports, and linings. There are three main areas which can be improved through the use of tunnel instrumentation. First, and of prime importance, is safety for men and the project. When unstable conditions occur, sets become distorted. Even without measurements, it is sometimes possible to tell when trouble is approaching. In effect, the set acts as a load cell. Distortions in the set indicate reinforcements may be required to maintain stability. Additional sets or rock bolts, if they are placed soon enough, may provide this stability. However, when large rock displacements occur in short periods of time, it could be too late. Figure 1 is an example of the difficulties encountered in stopping moving rock. To stop the movement and possible failure, large props were placed above the spring line and the massive concrete gravity buttress was constructed along the legs. Rock bolts from the buttress deep into the rock were also used in an attempt to stabilize the rock mass. However, this work is for a highway tunnel and eventually these props and buttresses must be removed.

Jan 1, 1971