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Metallurgy:

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    هانى شرف الدين
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     وسام الشكر

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    Metallurgy:

    METALLURGY:
    A) SOURCES OF METAL ORES
    An ore is a naturally occurring material from one or more metals can be profitably extracted. An
    ore is made up of a mineral containing the metal in question and other material called gangue.
    Some less reactive ores do occur in nature in the elementary form but most metals occur in an
    ore. The most common ores are oxides and sulfides.
    While the most abundant of material on the earth's surface are silicates these are not the most
    used ores. Note that silicates are very stable chemically and it is therefore difficult and expensive
    to extract metals from silicate ores.
    Three principle steps are involved in extracting a metal from its ore:
    1. Preliminary treatment or concentration of the ore
    2. Reduction, here metal is reduced to the metal
    3. Refining, metal is purified.
    1) CONCENTRATION OF ORE
    Many ores contain variable amounts of unwanted material called gangue composed of silica, clay,
    granite etc.
    Therefore some steps are needed to remove this gangue prior to reduction. The actual procedure
    used depends on the physical and chemical properties of the mineral and gangue. The first step is
    usually crushing of the ore. Followed by a procedure to separate the mineral from the gangue.
    A) washing this method of separation may be used when the mineral particles are more
    dense than the gangue.
    B) flotation used where the gangue is more dense than the mineral particles. Many cu, pb
    and zn ores are processed this way. Ore is mixed with oil and water. Mineral is wetted
    with oil and the gangue with water agitation produces a foam containing the oil and
    mineral. The foam floats to the surface and is skimmed off.
    C) magnetism ferromagnetic minerals can be separated by electromagnetic attraction.
    D) liquation heat to melting and pour mineral away from gangue. (Mineral is usually
    lower melting than the gangue)
    E) chemical pretreatment
    Al can be removed from bauxite by treatment with naoh
    Al2O3 + 2 OH- + 3 H2O Y 2 Al(OH)4
    -
    Solution is than filtered and the ph adjusted to ppt Al(OH)3
    from which pure Al2O3 can be recovered.
    2) REDUCTION OF METALS
    Most metals are obtained by high temp reduction (smelting) in these a flux (CaCO3) is
    added to remove the gangue left conc of the ore. The flux will form a slag which is molten
    at the temp of the process. The slag floats on the molten metal.
    CaCO3 + SiO2 Y CaSiO3 + CO2
    A) Roasting in Air for Metals of Low Reactivity.
    HgS + O2 Y Hg + SO2
    Cu2S + O2 Y 2 Cu + SO2
    b) reduction with carbon
    used on metals of intermediate reactivity
    e.g. Fe, Zn, Sn, Ni, Co and others of intermediate reactivity.
    High temp reduction usually involves CO not C as the reducing agent.
    2 C + O2 º 2 CO
    Fe2O3 + 3 CO º 2 Fe + 3 CO
    C) reduction with a more active metal
    reduction with c sometimes yields carbides instead of the metal. In these cases reduction
    with a more active metal solves the problem. e.g. Cr, Mn, U, W, Ti, Zr etc.
    Cr2O3 + 2 Al º 2 Cr + Al2O3 (THERMITE PROCESS)
    TiCl4 + 2 Mg º 2 MgCl2 + Ti (KROLL PROCESS)
    D) reduction with hydrogen
    used also when reduction with C fails
    WO3 + 3 H2 º W + 3 H2O
    e) electrolytic reduction
    used with very active metals
    hall process (see transparency) Al2O3 is dissolved in cryolite NaAlF6 resulting in a solution
    where Al +3 is reduced using a graphite electrode.
    ANODE: C+ 2 O-2 º CO2 + 4 eCATHODE:
    3 e- + Al+3 º Al
    F) ,/ vs ease of reduction
    which method to use for reduction can be correlated with the standard reduction potential.
    The more active metals have a more neg. õ/ metals of intermediate reactivity have an õ/
    OF -0.2 TO -1.00 v. metals of low reactivity have õ/ of -.2 or higher.
    3) PURIFICATION OF METAL
    the reduction of metals often produces impure metals. Further steps are needed to prepare
    the pure metal for use.
    A) liquation
    b) distillation
    c) preparation of a volatile compound followed by thermal decomposition.
    Ni (IMPURE) + 4 CO º Ni(CO)4 (g)
    Ni(CO)4 (g) + HEAT º Ni (PURE) + 4 CO
    d) zone refining
    e) electrolytic refining
    e.g. Cu, Sn, Pb, Au, Zn, Cr, Ni

  2. [2]
    هانى شرف الدين
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    عضو شرف


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    وسام الشكر

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    هذا الموضوع على هيئة ملف pdf

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    habloon
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    لو سمحت ياباشمهندس هانى بما انك تعمل فى مركز البحوث كنت عايز اسالك هل عندكم فى المركز اى دورات بخصوص حماية الفلزات من التاكل او دورات بخصوص الحماية الكاثودية ام لا؟!؟!!!!!
    مع خالص الشكر

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    من تواضع لله رفعه

  4. [4]
    هانى شرف الدين
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    عضو شرف


    تاريخ التسجيل: Nov 2005
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    وسام الشكر

     وسام كبار الشخصيات

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    لا يوجد حاليا بالمركز الا دورة اللحام الدولية وفى حالة وجود دورات بخصوص حماية الفلزات من التاكل او دورات بخصوص الحماية الكاثودية ساقوم بابلاغك فورا

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    habloon
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    اقتباس المشاركة الأصلية كتبت بواسطة هانى شرف الدين مشاهدة المشاركة
    لا يوجد حاليا بالمركز الا دورة اللحام الدولية وفى حالة وجود دورات بخصوص حماية الفلزات من التاكل او دورات بخصوص الحماية الكاثودية ساقوم بابلاغك فورا
    الف شكر ياهندسة

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    من تواضع لله رفعه

  6. [6]
    hassan_elshimy
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    جزالك الله خيرا

    السلام عليكم
    من فضلك يا باشمهندس هانى . ممكن تساعدنى فى ايجاد كتاب عن ال powder metallurgy او اى بحث عنه
    ولكم جزيل الشكر

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    Hassan El-Shimy

  
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