Table of Contents
Definition of Term Scorification: Scorification may be defined as a reduction and a partial or preliminary cupellation successively performed in the same container without removal of the container from the muffle until volatilization is stopped by the slag entirely covering the charge.
When is Scorification Assay Used
Scorification is the proper method of assaying copper mattes. It is also a good practice to first scorify, before cupelling, a lead button which has been reduced by crucible assay, and which is brittle or contains much copper or other bases. In doing this it will be necessary to add a small quantity of chemically pure test lead.
Assay by scorification is very satisfactory for base ores containing a large proportion of silver. The lead buttons from ores containing much copper or ores containing tin or nickel are best prepared for cupellation by preliminary scorification. Owing to the small amount of ore reduced (generally 1 /10 of an assay ton) scorification is not suitable for low grade gold ores.
Usual Charge
To scorify ordinary ores, take 1/10 of an assay ton (0.1) of ore, mix with 20 grams of chemically pure 
granulated test lead, and add on top of the mixed charge about 20 grams more of test lead. Sprinkle over the lead about 0.3 gram of borax glass. Use 2″ or 2½” scorifiers (Fig. 29). The size of the scorifier selected depends on whether 1/10 or 2/10 of an assay ton of ore is to constitute the ore charge.
Melting
Place the scorifier containing the prepared charge in the muffle, using scorifier tongs (Fig. 30), close the muffle and leave closed until the contents of the scorifier are thoroughly reduced. In a hot muffle this will probably take fifteen minutes. When they are properly reduced remove the muffle plug to admit air for oxidizing purposes. The ore gangue will appear as a ring of slag close around the edge of the scorifier, and this ring, as the volatilization of the lead and other bases progresses, will gradually converge to the center of the scorifier until finally the slag will cover the entire surface. All volatilizaiion will cease when this occurs, as the slag excludes the air from the lead. Care must be taken not to have the muffle too hot nor to allow the charge to oxidize too quickly, as in this event some of the silver values will be carried away with the fumes.
Pouring
Pour the contents of the scorifier into a pouring mold (Fig. 31) and when cool enough hammer the lead button free of slag. The button may now be cupelled if not too large or too brittle, and the bead may be weighed as in a crucible assay (Chapter II). If the lead button is hard and brittle rescorify by placing it in the same scorifier. Cover with test
lead, and sprinkle on top of all a small amount of borax glass (which will help as a flux). This rescorification is performed in exactly the same manner as the original process.
Rescorification may be performed in the original scorifier provided it is not weakened or too much corroded. The charge should be very fluid when poured, and it is advisable to close the muffle and raise the heat for a few minutes before pouring the contents of the scorifier into the mold.
