Prepara tus exámenes y mejora tus resultados gracias a la gran cantidad de recursos disponibles en Docsity
Gana puntos ayudando a otros estudiantes o consíguelos activando un Plan Premium
Prepara tus exámenes
Prepara tus exámenes y mejora tus resultados gracias a la gran cantidad de recursos disponibles en Docsity
Prepara tus exámenes con los documentos que comparten otros estudiantes como tú en Docsity
Encuentra los documentos específicos para los exámenes de tu universidad
Estudia con lecciones y exámenes resueltos basados en los programas académicos de las mejores universidades
Responde a preguntas de exámenes reales y pon a prueba tu preparación
Consigue puntos base para descargar
Gana puntos ayudando a otros estudiantes o consíguelos activando un Plan Premium
Comunidad
Pide ayuda a la comunidad y resuelve tus dudas de estudio
Ebooks gratuitos
Descarga nuestras guías gratuitas sobre técnicas de estudio, métodos para controlar la ansiedad y consejos para la tesis preparadas por los tutores de Docsity
aplicación de números romanos
Tipo: Apuntes
1 / 88
Esta página no es visible en la vista previa
¡No te pierdas las partes importantes!
We want dedicate this monograph to God, who has given us the life and strength to finish this research project, our teachers, who transmit us their diverse knowledge, especially of the field and subjects that correspond to our profession.
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 1
In our country, the most important place where Alluvial Auriferous Mining is carried out in Madre de Dios Department (Manu Province - Huepetuhe District), it is the most representative locality in terms of its wealth, production and problems generated with respect to this topic.
Gold is located in great amounts in the seas like other compounds, but it is not profitable to acquire it of that place. The normal thing is to extract it from the subsoil through the mines. It's not as simple as digging and getting a nugget. In this work we will see the sampling process, methods and technology that exist to obtain this metal.
The modeling of Placer Type Auriferous Deposit from Caychive River area, using Leapfrog software, would facilitate its exploitation with greater precision and optimization.
Gold is a malleable metal, yellow in color, having 19.3 as specific weight and a melting point of 1063 °C; is anticorrosive, insoluble in hydrochloric, sulfuric or nitric acid and can be dissolved in royal water. Its concentration in the upper lithosphere is 0.005 ppm. The gold content in different types of rock is as follows:
Rock ppm Gabbro, basalt 0. Diorite-andesite 0. Granite, rhyolite 0. Sandstone-conglomerate 0. Shale 0. Limestone 0.
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 2
Gold in Peru is mostly found in primary deposits such as:
1.1 Weathering and Erosion
Many mineralized gold-containing occurrences are subjected to mechanical and chemical weathering processes, whereby the ores disintegrate and decompose. The main weathering agents is water loaded with oxygen, carbon dioxide, salts and acids, changes in temperature and biological effects, mainly vegetation. The erosive process begins when the weathered material is removed from the parent rock, either as rock material dissolved in circulating water or as fragments displaced by gravity, wind or ice and subsequently deposited elsewhere.
Most of ore-minerals and rock are unstable, when are subjected to surface temperature and pressure conditions, lower than those to which they formed, tend to decompose into stable minerals under these new conditions.
Due to circumstances and processes, the material can take the transport or remain in place. However, there are some minorities that are more resistant than most, depending on their chemical and physical properties (hardness, cleavage, textural associations, etc.).
These chemically and physically stable varieties give rise to persistent detrital minerals that can concentrate on pleasures under favorable conditions.
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 4
The term "placer" is a term used by spanish miners in the Americas to characterize the gold deposits accumulated in sands, gravel and in the living bed of rivers.
Slingerland and Smith (1986) define pleasures as " a reservoir of detrital or residual minerals in grain, of economic value, which have been concentrated by mechanical agents ".
A placer deposit is composed of sand, gravel or other residual or detrital materials containing one or more minerals of economic value, which have been accumulated by weathering and mechanical concentration processes.
Its characteristics are:
Gold is in the native state, and varies in size from fine particles, difficult to recover, to nuggets of considerable size.
For the formation of economic placer deposits, the interaction of three phenomena is necessary to macro and meso scale:
a) A properly lithospheric phenomenon such as the presence of an enriched or pre- enriched source area capable of providing the economic interest minerals.
b) An environmental phenomenon of a climatic type, which may also be local, susceptible to release from low chemical resistance minerals (hydrolysis and oxidation), high mechanical resistance minerals.
c) A geodynamic - geomorphological phenomenon, capable of accumulating and preserving the released mineral elements.
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 5
It will also require the interaction of other hydraulic phenomena linked in space and time, which would be the cause of the release or detachment of particles and the transport and sedimentation of heavy minerals in river, lacustrine and marine basins.
Auriferous placers are perhaps the best known among these deposits types, but the minerals that fulfill these properties in varying degrees are: cassiterite, chromite, columbite, copper, diamonds, garnet, gold, ilmenite, magnetite, monazite, platinum, rutile, sapphire, xenotime and zircon.
SnO 2 Cassiterite (tin ore)
FeCr 2 O 4 Chromite (chrome ore)
(Fe,Mn)(Nb,Ta) 2 O 6 Columbite
C Diamond
FeTiO 3 Ilmenite
Fe 3 O 4 Magnetite
(Ce,La,Y,Th)PO 4 Monazite (REE-bearing mineral)
Al 2 O 3 Corundum-ruby (with Cr, red)-sapphire (with Co, Cr, Ti; blue)
YPO 4 Xenotime
ZrSiO 4 Zircon
Sulfides decompose easily when oxidized (they are not weather resistant), so they are rarely concentrated in pleasures. However, there are exceptions in paleoplacers of the Precambrian, probably because the Precambrian atmosphere was not oxidizing.
Placer deposits have been formed throughout geological time, but most are from the Cenozoic to recent. Most placers are small and often ephemeral because they occur on the earth's surface, usually at or above the base level for erosion, so that many of them are eroded and are only exceptionally buried to preserve themselves as paleoplacers.
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 7
2.1.3 Transported Placers They are deposits that are in the rivers currents beds or in valleys, conforming the most important deposits. Also called colluvial are defined as clastic accumulations from the melting water intermittent action, wind and gravity. Based on the agent type that has intervened in the formation of these deposits can be subdivided into deposits, glaciers and wind.
2.1.4 Fluvial Deposits or alluvial The unconsolidated lithologic complex containing sand, gravel, clay and silt is considered, deposited and / or currently depositing mainly along the rivers that drain the region. This deposits type is one of the most important in Madre de Dios. They are subdivided into:
Colluvial Deposits
They are materials transported by gravity, ice-thaw action and, mainly, by water. Its origin is local, rocks alteration in situ product and later transport like slope debris or solifluxion deposits.
They are often associated with unstable masses. Its composition depends on the rock from which they come, being formed by angular and heterometric fragments, generally of coarse size, encompassed in a silty clay matrix. Its thickness is usually low, although it can be very variable.
These materials' resistance is low, especially in the contact zone with the rocky substrate, and when high interstitial pressures develop as an intense rains result.
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 8
Figure 2.1.4–1.- Colluvial deposits’ typical chart
Alluvial Deposits
They are materials transported and deposited by water. Their size varies from clay to thick gravels, pebble and blocks. The thicker facies have rounded edges. They are distributed in stratiform form, with a certain classification, with a wide density range. They are very developed in the temperate climates, occupying fluvial channels and valleys, plains and alluvial fans, terraces and paleochannels.
They are highly anisotropic soils in their distribution, their properties are closely related to granulometry. Its continuity is irregular, being able to have high contents in organic matter in certain means. The permeability depends on the granulometry and generally present a high phreatic level. Alluvial deposits constitute a source of building material resources, especially as aggregates.
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 10
Coastal deposits
They are materials formed in intertidal zone by the mixed action of continental and marine environments, influencing in this case the fluvial currents, waves and tides. Predominant fine sands and silts, being able to contain abundant organic matter and carbonates. The finest sediments, sludge and organic matter are characteristic of delta and estuary areas. In general, the consistency of materials is soft to very soft and very anisotropic. They may present crusting, but the main characteristic is their high compressibility.
Figure 2.1.4–4.- Supe/Lima littoral deposit’ typical chart
Glacier deposits
They are deposits transported and deposited by ice or thawed water. They are formed by tillite and moraine. Its composition is very heterometric and the distribution is highly erratic. Fluvial-glacial deposits contain fractions from coarse gravel to clays; are somewhat classified and their granulometry decreases with distance from the glacier. However, those of lacustrine-glacial origin have finer fractions, predominating clays and laminated structures, typical of varve clays.
Heterogeneity and anisotropy are typical characteristics of these deposits, since they coexist from clays to coarse gravels and large blocks. As the permeability is directly related to the granulometry, these soils are very sensitive to the interstitial pressure increases produced
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 11
by torrential rains and by thawing. In these deposits are very frequent phenomena of solifluction and slopes instability.
Figure 2.1.4–5.- Glacier deposit’ typical chart
Arid and desert climates deposits
Arid environments have a number of environmental implications, such as deep drying, salt accumulation and high sediments mobility with the wind, which condition the properties of these soils, among which stand out:
Very low moisture content, resulting in unsaturated soils, with relatively high suctions.
Low in organic matter, so arid soils are poor for agricultural purposes.
Development of a rich salt crust; the loss of moisture by evaporation at the surface causes cementations by precipitation of salts.
Many arid soils have a wind origin, resulting in poorly graded soil, with a very loose structure.
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 13
Coastal or Marine Placers
They are defined as deposits located on the coasts, are heavy minerals concentrations that are formed by waves collision where the jump and the hangover drag the less heavy particles, concentrating the heaviest ones that come from the coastal marine terraces and the rivers. The heavy minerals consist mainly of: magnetite, chromite, ilmenite, monazite, zircon and occasionally gold particles.
Figure 2.1.4–7.- Sea placers forming zone
ESCUELA PROFESIONA DE INGENIERIA GEOLOGICA
Muestreo (metodología, tecnología) y dimensionamiento de Placeres Auríferos Page: 14
Table 2.1 – 1.- Mineral associations in placers.
Tabla 2.1 – 2.- Alluvial placers characteristics and shapes.
