Fire Assay Crucible For Melting Gold
For fire assaying ores, usually fluxes, materials such as borax, soda, silica are added to the ore. The amounts of each chemical added to the flux mixture depends upon the elements present in the particular ore, such as sulfur and iron. Usually lead, in the form of Litharge, is also added. The Fluxes (Except for the Lead, which is added for oxidization and sodium carbonate, which is added for de-sulfurization), are added for the purpose of lowering the melting point and imparting a homogeneous fluidity to the melted oxide impurities. The most common oxide impurities are silica, lime, and various metal oxides such as iron, copper, zinc, etc.. The ore samples with the fluxes are then added to a crucible, placed in a Assay Furnace, which has been pre-heated to 2,000 deg F, and left for a predetermined time, to melt or "fuse" the contents of the crucible. Then, the crucibles are removed from the assay furnace, the molten slag is carefully poured from the crucible, into a cast iron or graphite mold, such as cone shaped molds, and allowed to cool. The lead, containing the gold, being the heaviest material in the slag will be on the very bottom. When the slag cools, the hardened slag is removed form the mold and tapped with a button hammer to break away the lighter material, leaving only the lead button. The lead button is placed in a clay crucible called a Cupel. The cupel is designed to absorb the lead when heated to the melting point, and they are rated in the grams of lead they will absorb. So, the cupel's with the lead buttons are again placed in a Assay or Cupellation furnace, heated to about 2,000 deg F and the lead is absorbed into the cupel, leaving only a tiny gold bead. The cupels are removed from the furnace, allowed to cool and the gold bead is weighed.
Fire assay crucible for melting gold
Precious Metal Analysis
Crucible used for lab
Top diameter 95mm;Bottom diameter 55mm;High 135mm.
1. Refractoriness:1650 centigrade degrees;
2. Refractoriness under load:1420 centigrade degrees;
3. We can supply kinds of fire assay crucibles export level,customize was acceptable, samples and performance requirement.
Packaging and Delivery:
1. Wooden box
2. Export carton
3. WoodenPallet or Plastic Pallet
4. As Per Customer's Requirement
5. Any port in China.