Preparation - Gold Ore Crusher Posts Tagged preparation. preparation of ferrous sulphate from scrap iron. Nitrates There is a preparation sold as nitrate of iron, (probably so called.Cyanide Process. Cyanide process is also called as Macarthur-forest Process. It is the process of extracting gold or silver from the ores by dissolving in a dilute solution of potassium cyanide or sodium cyanide. This process was introduced in the year 1887 by the Scottish chemists naming Robert W. Forrest, John S. MacArthur, and William Forrest.