Balmat-Edwards

BALMAT-EDWARDS (EN: Balmat-Edwards; RU: Балмат-Эдуардс) is the ore field within the New York state, USA. It includes two deposits of the zinc ores: Balmat and Edwards. They have been discovered during the 1838, the intensive development is performed since the 1915. The ore-containing stratum is formed by the marbles, marbled limestones and dolomites, quartzites and crystalline schists, which are crumpled into the complex folds, and are often interbedded. The ore bodies are confined mainly to the layers of the marbled dolomites, and represent by themselves the curved tabular, ribbon-shaped, and lenticular depositions with bulges, constrictions, and numerous layered apophyses. Their length along the strike is up to 250 metres, along the dip is 600 metres and more. The thickness is 0.7-15 metres. The ores are metamorphosed.

The major ore minerals, namely, sphalerite and pyrite, form the macrocrystalline aggregates within the veinous mass, which is formed by the quartz, calcite, dolomite, and diopside. Galena, chalcopyrite, and pyrrhotite may be found in the form of the small venules and inclusions. The average content of Zn is 10%. The total reserves of ore are 16 million tonnes (1977). The extraction and processing of the ores are performed by the "Balmat" enterprise of the "St. Joes Minerals" company. The deposits are being developed by the underground method. The maximal depth of the development is 610 metres. The crushing of the ore is performed during the two stages: the first stage is performed underground within the jaw crushers, the second stage is performed at the beneficiation plant within the cone crushers with productive capacity of 250-400 tonnes per hour. The ore is delivered from the two bunkers (with the total capacity of 4000 tonnes) by the six belt conveyors into the rod mill, and then into the ball mill, which are working within the closed cycle with four hydrocyclones. There arrives for the flotation the material of the size class of 0.2 millimetres. There work within the cycle of the zinc flotation the six chambers for the major flotation, seven chambers for the monitoring flotation, three chambers during the first repeated cleaning, and two chambers during the second repeated cleaning. The usage of the X-ray analyzer permits to monitor the content of Ca and Mg within the zinc concentrate (up to 0.5% and 0.4% respectively). With the help of the fluorescent X-ray analyzer, there is performed the analysis of the dry briquettes for 11 elements simultaneously. The extraction of zinc into the 59% concentrate is 93.5%. The annual productive capacity of the enterprise is 1.3 million tonnes of ore (1977).