Mineralogical and Geochemical Characteristics and Designation of Key Beds for the Effective Surveys in the Jeonnam Clay Deposits

Abstract

Clayey ores of the Jeonnam province mainly consist of pyrophyllite (monoclinic), kaolinite (1T), and minor amounts of quartz, muscovite, and feldspars. Mineralogical studies revealed that two kinds of clay minerals were mainly produced from the volcanic sediments with similar ages and compositions. Kaolinite deposits sometimes contain neither diaspore nor corundum, but alunites are 1) *교신저자: kohsm@kigam.re.kr 유장한⋅고상모⋅문동혁 -266 -often found in the upper portions of the kaolin ore bodies. On the other hand, corundum and diaspore are commoner in the pyrophyllite deposits than the kaolin deposits. As ages of rock formations are becoming younger, amounts of pyrophyllite and kaolinite are rather radically decreased, and finally disappeared. But muscovite, quartz, and plagioclase feldspars are inclined to be preserved because of weak alteration. Most of clay ore bodies contain purple tuff beds on the uppermost portion, and silicified beds, tuff, and lapillistone are found in an ascending order in the most of clay quarries. Chemical analyses show that higher contents of Al2O3 might not necessarily be due to the argillization, since some tuffs contain higher Al2O3 contents originated from feldspars. SiO2 contents are fairly higher in the silicified beds than in those of adjacent formations, which might have been introduced from the ore bodies. And K2O contents are obviously lower than those of Na2O and CaO in the ores and their vicinities. Ignition losses of some of clays represent much higher contents than those of the ordinary ones because of the sporadic presence of alunite, diaspore and corundum which are accompanied with lots of SO4 and Al2O3 contents. REE (rare earth element) abundances of most of volcanics and clay ores show rather higher LREE (light rare earth elements) contents, and represent small to moderately negative Eu anomalies. Though most of ores ususally show milky white color, fine-grained and well bedded formations which could be easily discernible in the most of outcrop. But more distinct characteristics are desirable where rather massive ore bodies exist. Purple tuffs and silicified beds above the ore bodies would be useful as marker horizons/key beds since they have rather obvious lithology, extension and mineralogy than those of other adjacent formations.

Preparation of Granule Powders for Thermal Spray Coating by Utilization of Pyrophyllite Minerals

“…To evaluate fluidity of the heat treated pyrophyllite granule powders, flow rates were measured. After filling the hopper capable of holding the volume for 50 g with the prepared granule powder, it was made to flow by self weight, allowing measurement of flow rates according o the equation (1).…”

“…yrophyllite (Al 2 O 3 ·4SiO 2 ·H 2 O) is a 2:1 lamellar silicate clay mineral where an AlO 4 (OH) 2 octahedral layer is coupled between two SiO 4 tetrahedral layers. Our country as the major producer of pyrophyllite has a reserve of about 53 million tons 1,2) with its main use as a refractory material 3,4) , while its recent uses also include a low-expanding ceramic material, 5,6) glass fiber, cement, filler, plastic, tile, powder, china material, etc. 2) In particular, as it has a low ignition loss and lower crystal water content compared with kaolin family minerals, it can be used without conversion to chamotte, with easy pulverization as an altered mineral.…”