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معالجة خامات الذهب

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    الصورة الرمزية سياف 86
    سياف 86
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    جديد

    تاريخ التسجيل: Nov 2008
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    معالجة خامات الذهب

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  2. [2]
    سياف 86
    سياف 86 غير متواجد حالياً
    جديد
    الصورة الرمزية سياف 86


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    السلام عليكم

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  3. [3]
    عبد الرزاق سرور
    عبد الرزاق سرور غير متواجد حالياً
    جديد


    تاريخ التسجيل: Mar 2010
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    أين الموضوع يادكتور

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  4. [4]
    alshangiti
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    مشرف وإستشاري هندسة المناجم


    الصورة الرمزية alshangiti


    تاريخ التسجيل: Mar 2007
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    الموقع مليء با لمعلومات عن معالجة خامات الذهب

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    المهندس / يحيى بن محمد الشنقيطى

  5. [5]
    najeebali
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    عضو


    تاريخ التسجيل: May 2010
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    مَا يَلْفِظُ مِنْ قَوْلٍ إِلَّا لَدَيْهِ رَقِيبٌ عَتِيدٌ

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  6. [6]
    man utd.fc
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    جديد


    تاريخ التسجيل: Dec 2010
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    وين الموضوع يا حبيبنا

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  7. [7]
    alshangiti
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    مشرف وإستشاري هندسة المناجم


    الصورة الرمزية alshangiti


    تاريخ التسجيل: Mar 2007
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    Activated carbon is employed in many cyanidation plants to recover gold and silver fro m cyanide leach solutions from several processes: carbon in pulp (CIP), carbon in leach (CIL), and carbon in column (CIC). The activated carbon used in mining is called many times absorbent activated carbon and it’s a solid with high porosity and superficial area of more than 1000 m2/g. Each pore is about 10-20 Angstrom.
    The CIP process usually comprises the following operations: extraction, elution, electrowinning, and thermal reactivation. The absorption process is perhaps the most important part of the process since the optimization of extraction determines no only the amount of soluble gold lost in the residues from the plant, but also the amount of gold locked up in the plant, and the quantity of carbon reporting for elution and reactivation. Unlike most hydrometallurgical processes, the rate of extraction of gold from a pulp is slow, and the kinetics is very important in order to determine optimum conditions for the operation.

    Gold Cyanidation

    Gold Cyanidation.: Gold typically occurs at very low concentrations in ores - less than 10 g/t or 0.001% (mass basis). At these concentrations the use of aqueous chemical (hydrometallurgical) extraction processes is the only economically viable method of extracting the gold from the ore. Typical hydrometallurgical gold recovery involves a leaching step during which the gold is dissolved in an aqueous medium, followed by the separation of the gold bearing solution from the residues, or adsorption of the gold onto activated carbon. After elution from the activated carbon the gold is further concentrated by precipitation or electrodeposition.
    Gold is one of the noble metals and as such it is not soluble in water. A complexant, such as cyanide, which stabilizes the gold species in solution, and an oxidant such as oxygen are required to dissolve gold. The amount of cyanide in solution required for dissolution may be as low as 350 mg/l or 0.035% (as 100% NaCN).
    Alternative complexing agents for gold, such as chloride, bromide, thiourea, and thiosulphate form less stable complexes and thus require more aggressive conditions and oxidants to dissolve the gold. These reagents present risks to health and the environment, and are more expensive. This explains the dominance of cyanide as the primary reagent for the leaching of gold from ores since its introduction in the later part of the 19th century.
    The introduction of cyanide leaching two centuries ago revolutionized the processing of gold and silver ores. Gold is dissolved as an aurocyanide complex in oxidizing alkaline cyanide solutions. The reaction is expressed in its simplest form by the Elsner equation:
    4Au + 8NaCN + O2 + 2H2O = 4Na[Au(CN)2] + 4NaOH
    The reaction of silver sulphides, commonly associated with gold ores, is not quite so straight-forward, but is usually expressed in the following manner:

    Ag2 + 4NaCN = 2NaAg(CN)2 + Na2S
    The reaction of silver Sulphide with sodium cyanide is reversible and does not proceed far unless sodium sulphide is remover from the system or an excess of free sodium cyanide is available to drive the reaction to the right.
    Fortunately sodium sulphide is sensitive to oxidation, discomposing via side reactions to sulphocyanate and thiosulphate. The point is that oxygen is an indispensable ingredient for successful cyanide leaches of gold as well as the sulphide compounds of silver. Nevertheless, silver halides are attacked by cyanide without the necessity of oxygen.
    Although the affinity of cyanide for gold is such that it is extracted preferentially, cyanide will also form complexes with other metals from the ore, including copper, iron and zinc. The formation of strongly bound complexes such as those with iron and copper will tie up cyanide that would otherwise be available to dissolve gold.
    Copper cyanides are moderately stable; their formation can cause both operational and environmental concerns, as wastewater or tailings from such operations may have significantly higher cyanide concentrations than would otherwise be present in the absence of copper. High copper concentrations in the ore increase costs and lower recovery efficiencies by requiring higher cyanide application rates to compensate for reagent that complex with copper rather than gold.

    الأخوة الاعزاء هده من الموقع وهناك الكثير من المواضيع لكن عليكم البحث

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    المهندس / يحيى بن محمد الشنقيطى

  8. [8]
    alshangiti
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    مشرف وإستشاري هندسة المناجم


    الصورة الرمزية alshangiti


    تاريخ التسجيل: Mar 2007
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    Gold Processing Plant, Carbon In Leach (CIL) Plant


    A Carbon In Leach Gold Recovery Plant. This plant processes 4 million tons of ore per year with an average gold ******* of 0.043 ounces of gold per ton of ore. Approximately 85% of the gold is recovered in the plant. The crushed ore is fed to tanks of cyanide solution, where the gold is dissolved in the cyanide. The pregnant solution is then transferred to a series of tanks, where carbon is added. The gold is adsorbed onto the surface of the carbon. The carbon, with gold attached, is removed by screening. The gold bearing carbon is then introduced into a heated sodium hydroxide-cyanide-water solution where the gold is dissovled. This concentrated solution is passed through a series of electrowinning cells, where the gold quickly plates (in about 3 minutes) onto the stainless steel cathodes. The gold is washed from the cathodes, with high pressure sprays, dried and melted, to be poured into molds for gold bricks, or ingots.

    A flowsheet, showing the Carbon In Leach (CIL) process This circuit utilizes a thickener, to maintain a constant percent solids in the ore feed, necessitating less water used in the process, smaller tanks and a smaller pond. It also gives much more control over the process that a conventional CIL plant without a thickener. The CIL process is viable if there is sufficient gold *******, carbonates/clays in the ore which will "rob" some gold in solution, and it leaches in 8-13 hours. A Stainless Steel Cathode from the electrowinning cell in the gold room. Notice the gold that has plated onto the surface of the stainless steel mesh. The next step is to wash the gold from the cathode with a high pressure water sprayer, then melt it and pour it into a mold where it will be in a

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    المهندس / يحيى بن محمد الشنقيطى

  9. [9]
    alshangiti
    alshangiti غير متواجد حالياً

    مشرف وإستشاري هندسة المناجم


    الصورة الرمزية alshangiti


    تاريخ التسجيل: Mar 2007
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    الأخوة الاعزاء كما قلت سالفا هده المواضيع هى طريقتين من طرق استخراج الدهب باستخدام السيانيد وهى موجودة فى الموقع وهناك اكثر من دلك انصحكم با لبحث

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    المهندس / يحيى بن محمد الشنقيطى

  
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