Skład mineralny a własności surowcowe iłów neogenu południowej części Ziemi Lubuskiej

Abstract

Przedstawiono wyniki analizy porównawczej składu mineralnego i własności surowcowych skał ilastych neogenu – serii poznańskiej i serii Gozdnicy – eksploatowanych przez przemysł ceramiczny. Wyodrębniono dwie grupy surowców: kaolinitowe i beidelitowe, podano ich skład mineralny, właściwości technologiczne i własności porowatego i spieczonego tworzywa ceramicznego. Określono wpływ zawartości minerałów ilastych i kwarcowej frakcji piaskowej na własności surowcowe tych iłów.

MINERAL COMPOSITION VERSUS RAW MATERIAL PROPERTIES OF NEOGENE CLAYS FROM SOUTHERN PART OF THE ZIEMIA LUBUSKA

The mineral composition and ceramic properties of kaolinite and beidellite raw materials (27 and 39 samples, respectively) exploited south of Zielona Góra (Lower Silesia) for the use in building ceramics industry were studied.

Kaolinite raw materials contain 45 to 85% of clay minerals occurring in the form of kaolinite – beidellite – illite and kaolinite – beidellite assemblages, and 10 to 50% of detrital quartz including 0.4 to 33% (11.4% on the average) of quartz sand.

Beidellite raw materials contain 45 to 90% of clay minerals occurring in the form of beidellite – kaolinite – illite and beidellite – illite – kaolinite assemblages and 5 to 50% of detrital quartz including 0.3 to 23% (7.4% on the average) of quartz sands. Both groups of raw materials also contain muscovite, iron oxides and sulfides, subordinate amounts of feldspars and, sometimes, siderite.

Kaolinite raw materials are usually medium-plastic (Fig. 1). Drying shrinkage equals 5.0 to 11.3%. Sintering temperature ranges from 1000–1250°C to 1200–1300°C, depending on the share and proportion of clay minerals (Figs. 2 and 3).

It is possible to made of them ceramic porous material with average water absorption ranging from 16 to 6 weight %, and sintered material with water absorption from 6 to 0 weight %. The optimum physical parameters characterize porous and sintered material made of raw materials containing 40–60% of clay minerals and less than 10% of quartz sand (Tab. 1, 3–4).

Beidellite raw materials are usually plastic or highly plastic and with drying shrinkage oscillating from 6.5 to 11.3%. Their sintering temperature is lower than that of kaolinite raw materials, ranging from 980–1170°C and most often from 1100 to 1150°C. From these raw materials are made three kinds of ceramic materials: 1 – porous, with water absorption usually ranging from 13 to 6 weight %, 2 – sintered, with water absorption ranging from 6 to 0 weight %, and most often from 6 to 2 weight %, and 3 ­– thermic ally swelled. The porous and sintered materials with optimum physical properties were obtained from raw materials containing 50 to 60% of clay minerals and less than 10% of quartz sand. Swelling is most intense in the case of beidellite raw materials containing more than 70% of clay minerals and some admixture of iron sulfides.