PRECIOUS METAL ASSAY LABORATORY

Introduction to Assaying

The assaying process is a necessary step to determine the quantity of precious metals present in an alloy. Cupellation is one operation of the assay process in which a sample of gold, wrapped in lead foil, is melted in a special crucible known as a cupel: this cupel has the capacity of absorbing the non-precious metals contained in the gold alloy. The weight of the gold alloy sample is usually about 250/1000. Although this is the most ancient method to determine the purity of an alloy, assaying by means of cupellation gives greater precision than more modern methods (fluorescent or x-ray spectrophotometry) and is considerably less expensive.

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THE ASSAY LABORATORY

WEIGHING THE SAMPLE

• Weight range : from 0 to 82 gr ( indicates up to five decimal figures )
• Weight range : from 0 to 220 gr ( indicates up to 4 decimal figures

• Max. capacity to drill : 10 mm
• Speeds : n°4
• Spindle speeds : 450/rpm
• Ground base dimensions : 230×270 mm

• Overall dimensions : 890x710x800 mm
• Weight : 76 Kg

CUPELLATION

• Max. working temperature : 1350°C
• Silicon carbide muffle : 155x205x80 mm
• Number of cupels : n°12 diam 25 mm
• Resistances : ceramic
• Power : 8.5 Kw
• Dimensions : 830x950x1850 mm

ANNEALING

• Power supply : three phase
• Total power : 1.5 Kw
• Water consumption : 1-2 lt/1’
• Dimensions : 750x450x1300 Kg
• Weight : 120 Kg

ACID ATTACK

• Number of 6 place ovens : n°2
• Power : 4 Kw
• Dimensions : 1150x650x1820 mm
• Weight : 90 Kg

SCRUBBING OPERATION

• Power : 0.25 Kw
• Overall dimensions : 653x700x2165
• Weight : 65 Kg

FOUNDRY

MEDIUM FREQUENCY INDUCTION MELTING FURNACE TYPE FIM/12NT

• Rapid interchangeability of the crucible
• Protection of the metal while melting by an inert gas
• Manual extraction of the crucible using the appropriate pincers
• Automatic temperature control of the metal
• Absorbed power : 12 kW
• Power output : 11.4 kW
• Required quantity of the cooling water : 20 lt/min
• Capacity of the crucible : 17 Kg of Au
• Melting time : 15 minutes
• Dimensions : 485x510x915 mm (L x W x H)
• Weight : Approx. 216 Kg

• Power output : 15 kW
• Working frequency : 5 Khz
• Power-supply tension : threephase
• Power factor (cosF-i) : 0.9
• Required cooling power (generator/furnace) : 6,500 Kcal/h
• Minimum water cooling capacity : 15 lt/min
• Min pressure for the cooling water pump : 3 Bars
• Cooling water inlet temperature : 30° + 35°C

• Nominal tension : depends on where the machines
• Allowed fluctuation of the electrical mains : +/- 10%

Water chilling unit model FRIGO/20

• Water cooled induction melting furnaces
• Trichloroethylene degreasing machines
• Brazing belt furnaces
• Deoxidation furnaces
• Fumes condensors for hollowing and refining plants

Aqua regia

Gold Refining

REFINING TUMBLER UNIT TYPE IAO/BR50

The plant is mainly made up of :

• Polypropylene hood designed to the recover any acid losses
• PPL tumbler with a useful capacity of about 100 litres
• No. 2 Graduated tanks for HCl and HNO3.
• No. 1 PPl tray where two 100 lt containers for HCl and HNO3 acids are stored.
• No. 2 Filter units on wheels with a compressed air diaphragm pump to transfer the solutions. One 450 mm high, the second 750 mm.
• No. 1 100 lt cementation unit.
• No. 1 Control panel

• Power supply : Single – phase.
• Power : 0,8 Kw
• Overall dimensions : 2600 x 1200 x 2500 mm. ( Length – Width – Height).
• Weight : 375 Kgs

NEUTRALIZATION TOWER FOR FUMES MODEL TLF/850

• Power supply : three-phase.
• Power : 3 kW
• Overall dimensions : 1500x1200x3500 mm (length-width-height).
• Working weight : 350 kg

Water treatment Dept.

RESIN RECOVERY SYSTEM TO RECOVER TRACE PRECIOUS METALS

• n.1 Pneumatic valve, PVC/EPDM, NC DN32-028
• n.2 Ball valves, PVC/EPDM, 546- DN32
• n.1 Pneumatic level regulator, PVC/EPDM, with flange DN100
• n.1 Centrifugal pump, threephase, 1.1 kW, PVDF, with PP base
• n.1 Valve 546-DN40
• n.1 PVC flowmeter, 1000 lt/hour
• n.1 Pressure gauge, 2.5 Bar, with trap
• n.1 Non-return valve, PVC/EPDM, DN15
• n.1 Pneumatic valve, PVC/EPDM, NC DN15-028
• n.1 Valve 546-DN15

• n.3 Columns, 2 round bottoms DN300, 3 DN25 flanges, 1 DN100 handrail, PP nozzles
• n.1 Column resting base
• n.4 Pressure gauges with traps
• n.22 Valves 546-DN15
• n.1 Pneumatic valve 028 DN15

• n.1 Pneumatic pump, PP body with flow rate regulator
• n.1 Valve 546-DN25
• n.1 Non-return valve 303 DN25
• n.1 Pneumatic level control

ACID WATERS NEUTRALISATION PLANT MODEL IN/A

• Agitator to stir the incoming solution

• The filter press is used to filter water and slime in order to recover precious metals. The press is fitted with a 700 lt pneumatic pump. The components of the filter press, from the smallest to the largest, are single-block structures that are electrically welded, machined and carefully inspected; the design has allowed very low stress levels, even under maximum operating pressure.
• The heads and longitudinal bars are plated with stainless steel or other metals depending on the chemical properties of the solutions to be filtered.
• The cloths, the shape and the dimensions of the plates, as well as the materials used inside the filter elements, constitute the most important part of a filter press. The choice of these elements is the result of years of experience on the part of those who are familiar with these problems.
• The pump is provided with an electronic level control probe for the automatic starting and stopping of the plant.
• The solutions exiting the filter press contain chlorides, nitrates and sodium sulphates that can be concentrated or diluted with other waste waters.

• Power supply : three-phase
• Power : 1 Kw
• Plate dimensions : 320×320 mm
• Number of plates : 50
• Volume of slime contained : 100 lt
• Overall dimensions : 2680x580x830 mm
  • Type of plate-locking system : mechanical

Special Notes:

• Chemical composition of the material to be refined would be ideal.
• Initial form of the material as in old jewelry, fluvial dust, gold scraps, etc.
• Starting purity, including quantity of Au and Ag.
• Required final purity of the material (IE 999,5)
• Required final form you require(IE Ingots, Grain etc.). If you require Ingots, kindly specify the weight ( 1 Kg, 2 Kg, 500 Gr, Etc).

• Average silver content must not exceed 15-18 %

• This is a standard setup (equipment can/will change according to specific requirements)
• This information is intended only as a guideline to those who want to have an approx. idea at investment levels for such a project with these daily quantities.
• Some refining situations may not require all the listed equipment, others will require additional units, which is why more technical infformation is required (i.e. materials, purities etc.) before issuing a formal quote.
• This webpage should not be considered a fomal quote.

Optional Installation & Training

€ 960.00/Day plus flight/travel related expenses