Day 56 Gold Mining, Metallurgy and Prospecting I

Introduction

We are going to show you the basic theory and methodology you need to find where gold is present, how to identify it and what alternatives there are for the extraction of gold via panning or other. In short, this site will show you everything you need to know about gold prospecting. Although we’ll explain to great extend the “how to” of searching for mineral deposits within ore veins, this guide considers free gold (Gold Placers of various types) as the main source of this precious metal.

Mining extraction and metallurgy of gold has been pursued with great interest since it developed intrinsic value as a result of its economic and physical properties, its decorative appeal and its scarcity. During much time gold has been the most attractive metal on the world, and still to this day is one the ones most fever and many developments and new ideas have appeared as a consequence of its huge value as an economic metal.

The gold mining industry has grown considerably, and it appeared to the writer that the present would be a propitious time to bring out some guides in order to understand gold prospecting and gold mining. What has been goal of the site is to make “Prospecting for Gold” a compendium, in especially concrete form, of useful information respecting the processes of winning from the soil and the after- treatment of gold and gold ores, including some original suggestions. Practical information, original and selected, mining jobs are given to mining company directors, mine managers, mill operators, and prospectors. In each part, will be found a large number of useful hints on subjects directly and indirectly connected with the gold mining.

All the information should be very useful and surely is original, and each reader will be able to understand the difficult task of processing gold ores found in the veins that bear it. You’ll learn the art of extracting valuable metals from gravel placers.

Here, you can learn about metal detecting as well as gold panning. You get to learn why gold placers will form where they form. You’ll learn how to look and how to find gold placers (that’s prospecting!) and analyze it.

Those unfamiliar with prospecting and mining will find a great Glossary of the Mining Trade’s Terms. The characteristics of an ore deposit and its minerals assemblages (mineralization) determine mining methods, extraction process (recovery methods & equipment needed), and the performance of all chemical processes involved in gold extraction. Thus, a good knowledge of an ore is required to develop a gold extraction and the efficiency of the process.

The gold mineralogy can offer the following variations:

  • Gold occurrence, showings.
  • Gold particle size and distribution.
  • Type of gangue.
  • Mineralogical association.
  • Changes in mineral.
  • Changes during the time.

Classifications of gold-bearing materials

According to their mineralogical and historical characteristics the gold- bearing material can be classified as:

  • Placers.
  • Free milling ores.
  • Oxidized ores.
  • Silver-rich ores.
  • Iron sulphides.
  • Arsenic sulphides.
  • Copper sulphides.
  • Antimony sulphides.
  • Tellurides.
  • Carbonaceous.

– See more at: http://miningandmetallurgy.com/gold/html/classifications_of_gold-bearin.html#sthash.V3tflhPX.dpuf

Classifications of gold-bearing materials

According to their mineralogical and historical characteristics the gold- bearing material can be classified as:

  • Placers.
  • Free milling ores.
  • Oxidized ores.
  • Silver-rich ores.
  • Iron sulphides.
  • Arsenic sulphides.
  • Copper sulphides.
  • Antimony sulphides.
  • Tellurides.
  • Carbonaceous.

– See more at: http://miningandmetallurgy.com/gold/html/classifications_of_gold-bearin.html#sthash.V3tflhPX.dpuf

 

Classifications of gold-bearing materials

·          

According to their mineralogical and historical characteristics the gold- bearing material can be classified as:

  • Placers.
  • Free milling ores.
  • Oxidized ores.
  • Silver-rich ores.
  • Iron sulphides.
  • Arsenic sulphides.
  • Copper sulphides.
  • Antimony sulphides.
  • Tellurides.
  • Carbonaceous.

Placers

In geology, a placer deposit or placer is an accumulation of valuable minerals formed by gravity separation during sedimentary processes. The name is from the Spanish word placer, meaning “alluvial sand”.  Placer mining is an important source of gold, and was the main technique used in the early years of many gold rushes, including the California Gold rush. Types of placer deposits include alluvium, eluvium,  beach placers, and paleoplaceres.

Placer materials must be both dense and resistant to weathering processes. To accumulate in placers, mineral particles must be significantly denser than quartz (whose specific gravity is 2.65), as quartz is usually the largest component of sand or gravel. Placer environments typically contain black sands, a conspicuous shiny black mixture of iron oxides, mostly magnetite with variable amounts of ilmenite and hematite. Valuable mineral components often occurring with black sands are monazite, rutile, zircon, chromite, wolframite, and cassiterite.

Free Milling Ores

Ore that contains sufficient valuable mineral to be treated by milling process.

OXIDIZING ORES   

When ore deposits are exposed to the oxidation zone they are weathered and altered with the country rocks.

·       The surface waters oxidize many ore minerals and yield solvents that dissolve other minerals.

·       An orebody thus becomes oxidized and generally leached of many of its valuable materials down to the groundwater table, or to  depth where oxidation cannot take place.

·       The effects oxidation may, however, extend far below the one of oxidation.

·       As the cold, dilute, leaching solutions trickle downwards, they may lose a part or all of their metallic content within the zone of oxidation to give rise to oxidized ore deposits.

·       The oxidized or near-surface part of an orebody is made colorful due to the oxidation of sulfides to oxides and sulfates.

·       As the down trickling solutions penetrate the water table, their metallic content may be precipitated in the form of secondary sulfides to give rise to a zone of secondary or supergene sulfide enrichment.

·      The lower, unaffected part of the orebody is called the hypogene zone.

·      In some places the supergene zone is absent and in rare cases the oxidized zone may be shallow or lacking (as in some glaciated areas undergoing rapid erosion).

·      Special conditions of time, climate, physiographic development and amenable ores are necessary for the process of oxidation and supergene enrichment to be effective.

·      Such ores occur in most of the non-glaciated land areas of the world.

 

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