Zinc and lead ores
The area of northern and north-eastern margin of the Upper Silesian Coal Basin has a long tradition of zinc and lead mining, dating back to the Middle Ages. Deposits occurring in that area are related to carbonate rock formations of the Silesian-Cracow region with Permo-Mesozoic succesions resting monoclinally on the Paleozoic basement. Rock hosting Zn-Pb mineralization range in age from the Devonian to Jurassic. Resources of economic importance are mainly related with ore accumulations in the so-called ore-bearing dolomites of the Muschelkalk (Middle Triassic). The ores occur in the form of pseudo-layers, subhorizontal lenses and nest-like replacements. The Silesian-Cracow region is regarded as the world's largest area of occurrence of Zn-Pb deposits of the so-called Missisipi Valley type (MVT).
Four areas of Zn-Pb ore deposits are recognized in the Silesian-Cracow region: Chrzanów, Olkusz, Bytom and Zawiercie regions. The Balin-Trzebionka deposit in the Chrzanów region and the Olkusz and Pomorzany deposits in the Olkusz region are currently under exploitation. Zn-Pb deposits of the Bytom region are of historical and scientific importance only. The deposits have been exhausted in result of exploitation conducted since the Middle Ages and now comprise some subeconomic accumulations of mainly oxide ores. Exploitation of deposits of the fourth region (Zawiercie) did not start up to now. Location of Zn-Pb ores deposits in Poland are presented on the general and detailed maps.
Zn-Pb concentrations occur also in copper ores of the Zeschstein copper-silver deposits in the Fore-Sudetic Monocline. These concentrations are high enough for lead recovery in the course of copper concentrate treatment in smelters. According to the data provided by the KGHM Polish Copper S.A., in 2010 the copper processing was accompanied by recovery of 22 thousand tonnes of lead.
The highest increase of sulfide Zn-Pb ore resources can be expected in the Silesian-Cracow region. Prognostic resources in Olkusz region amounted to 50 million tonnes and in Zawiercie region to 15 million tonnes as of 31.12.2009(1). Zinc oxide ore (galmans) prognostic resources are assessed to be equal 60 million tonnes, including 51 million tonnes in abandoned deposits and 9 million tonnes in mining dumps.
Estimates of resources of Zn-Pb ores of the Silesian-Cracow region were markedly changing during the last 50 years. These changes resulted on one hand from intense exploration of the deposits and on the other – from crossing out the resources of zinc oxide ores (galmans) from the official records of domestic resources of mineral raw materials. This decision to cross out the resources was connected with high occupational and environmental hazards associated with technology used at that time in oxide ore processing. The problems in technology were finally solved. Therefore, it appeared necessary to introduce special criteria for classification of Zn oxide ore resources not meeting those of the sulfide ores. Such separate criteria for Zn oxide ore resources were established by the Regulation of the Minister of the Environment on classification for mineral reserves and resources of 9 January 2007. Table 1 shows resources and the current state of exploration and development of Zn-Pb deposits.
Anticipated economic resources of Zn-Pb ores for 31 December 2010 were equal 79.87 million tonnes of ores yielding 3.57 million tonnes of zinc and 1.52 million tonnes of lead.
In 2010, Polish mines extracted 2,450 thousand tonnes of ores yielding 89 thousand tonnes of zinc and 35 thousand tonnes of lead. The domestic production of ores is too small for full use of production potential of Zn-Pb processing plants.
The figure given below shows changes in resources and production of zinc and lead ores in Poland in the years 1989-2010.
In 2010 import of zinc amounted to 197 thousand tonnes (increased by 15 %), export amounted to 113 thousand tonnes (decreased by 21 %). Import of lead was equal 59 thousand tonnes (increased by 75 %), export of lead decreased by 24 % and was equal 87 thousand tonnes.
Zinc and lead processing activities give rise to fairly large waste stream. In 2010, the processing generated 1.43 million tonnes of post-flotation waste which was disposed in tailing ponds.
- B - for solid minerals - mine in building process, for fuels - prepared for exploitation or trial period of the exploitation
- E - exploited
- G - underground natural gas storage facilities
- M - deposit crossed out of the annual report of mineral resources during analized period
- P - deposit covered by preliminary exploration (in C2+D category, for fuels – in C category)
- R - deposit covered by detailed exploration (in A+B+C1 category, for fuels – in A+B category)
- Z - abandoned deposit
- T - deposit exploited temporarily
- K - change of the raw material in deposit
Prepared by: Agnieszka Malon, Stanisław Z. Mikulski, Sławomir Oszczepalski, Marcin Tymiński
(1) S.Z. Mikulski, B. Strzelska-Smakowska, W. Retman, 2011 - "Rudy cynku i ołowiu" w "Bilans perspektywicznych zasobów kopalin Polski wg stanu na 31 XII 2009 r." pod red. S. Wołkowicza, T. Smakowskiego, S. Speczika. PIG-PIB Warszawa.