Chapter 27 Lead–zinc–silver deposits of Myanmar

Abstract

Before 1960 the Pb–Zn–Ag mines in Myanmar were an important source of foreign exchange. Almost the entire output of lead and zinc came from the Bawdwin Mine which, before 1942, was ranked as the sixth-largest producer of lead in the world (Ministry of Mines 1970). In 1938 Myanmar's output of refined lead, zinc concentrates and silver was 76 590 tons, 65 928 tons and 6 230 000 ounces, respectively. By 1986 output levels had fallen to 5948 tons of lead, 7393 tons of zinc and 576 000 ounces of silver. These figures represent a dramatic decline in production from the Bawdwin Mine and Namtu Processing Plant, which Soe Win (1994) has considered to be due to the failure to identify new reserves and inadequate investment in mine facilities. In the past, the Namtu–Bawdwin mining complex produced refined silver, lead and zinc concentrates, copper matte, nickel speiss and antimonial lead. The rich sulphide ore, previously mined underground at Bawdwin and treated at Namtu, yielded a lead concentrate averaging 51.3% Pb, 14.1% Zn and 1.16% Cu and a zinc concentrate averaging 26.1% Zn and 18.1% Pb. Currently, the oxide ore (‘halo ore’) from the open pit only is processed at Bawdwin, to yield a concentrate averaging 41.73% Pb, 9.03% Zn and 3.06% Cu. The lower ore grades present a problem for the old Namtu smelter, which was designed for processing sulphide ore and requires lead concentrates to have a minimum content of 57% Pb with 10–15% Zn and 1–2% Cu. A new blast furnace has been installed capable of smelting lead concentrates as low as 40% Pb, with a tolerance of up to 8% Zn and 3% Cu and with a rated capacity of 50 tons/day (Than Htay 2002). In addition, a zinc fuming plant will produce zinc oxide from zinc slags. …