Fire Assay Method Commonly Used Utensils And Equipment

(1) Test crucible

Melting crucible Assaying Assaying is generally referred to as crucible made of refractory clay. General requirements for assay crucibles are: having sufficient refractory degree, that when heated to high temperatures in the crucible same soft or fallen down; when heated can maintain sufficient pressure, forceps or fork out at the time not break ; resistant to the chemical action of the melt, it will not be subject to include strong acids, alkalis, or various melt contains a lot of lead oxide, including corrosion, leakage through the crucible.

(2) ash pan

Ash pan is to absorb lead oxide (or bismuth oxide) porous refractory containers used cupellation lead button (or bismuth deduction) when. There are three commonly used ash pan: cement ash pan, ashes - cement ash pan and ash pan magnesia.

① cement dust pan with 400,500 number of portland cement, plus 8 to 12% water, mixing, pressing on the gray dish machine. Portland cement component containing CaO60 ~ 70%, A1 2O3 4 ~ 7%, SiO2 l9 ~ 24%, Fe2O3 2 ~ 6%. Cement is inexpensive conventional materials. Cement ash pan hard, not easy to crack, but the precious metal after the loss of two larger than that when the ash blowing.

② ashes ash pan and ash - cement dust pan with cattle bone ashes burning, ground, and then burning the resulting, where organic matter must all be removed. Its composition was 90 percent calcium, 5.65% calcium oxide, magnesium oxide 1%, 3.1% calcium fluoride. Fineness of ashes is less than 0.147mm, 0.088mm which should be more than 50%. Made with pure ashes loose ash pan, it can be used for coarse gold, crude gold gray blow. Assaying analysis generally mixed ash pan ashes and cement, ashes and cement mix in different proportions, plus 8 to 12% water, the gray dish machine pressed. Different people do different test result, some believe 3: 7 is good, there are thought to be 4: 6 or 5: 5 good. Ashes - is harder than pure cement gray ashes ash pan dish, but, soft gray dish than cement. With ashes - cement gray ash pan to blow, the loss of gold and silver than gray cement smaller pan. Preparation of the ashes of more trouble to go through burning, ground several procedures to be made.