Amakusa Pottery Stone Research Articles

天草陶石鉱床の特徴と鉱床生成に関する考察

天草陶石鉱床の特徴と鉱床生成に関する考察

Hydrothermal alteration and radiometric age of zircon from the Amakusa pottery stone deposit

Hydrothermal alteration and radiometric age of zircon from the Amakusa pottery stone deposit

Clay Minerals in the Amakusa Pottery Stones and Some Features of Their Pottery Clays.(I)

Clay Minerals in the Amakusa Pottery Stones and Some Features of Their Pottery Clays.(I)

Hydrothermal alteration at the Denbekoba deposit of Amakusa pottery stone.

Mineral parageneses and high-low inversion temperature of quartz at the Denbekoba deposit of the Amakusa pottery stone have been investigated by X-ray powder diffraction, differential thermal analysis and polarizing microscopy. The main constituent minerals of the pottery ores are quartz and sericite. Kaolinite, dickite, tosudite, rectorite, calcite, siderite and residual feldspar are also contained in some ores. The deposit is considered to have been formed by hydrothermal alteration subsequent to the intrusion of rhyolitic magma. The central zone of the alteration is rich in sericite, kaolinite and rectorite. Tosudite is abundant in the intermediate zone between the central zone and the weakly altered zone. The central zone appears to have been subjected to conspicuous alteration at a late stage. The high-low inversion peak in the DTA curve for the quartz is broad and the peak temperature is 4-23°C lower than that of standard quartz. Quartz samples in the central zone have higher inversion temperature as compared with those in the outer alteration zones. Moreover, the quartz samples in the central zone also show another low-temperature broad peak which may be due to the quartz having formed in the late stage of the alteration

Constituent Minerals and Their Mineralogical Properties of Amakusa Pottery Stones

Constituent Minerals and Their Mineralogical Properties of Amakusa Pottery Stones

Bending Creep Properties of Fired Amakusa Pottery Stone and Effects of Alumina Addition

Bending creep rates for fired specimens (3×1×0.2cm) of Amakusa Touseki (pottery stone, chiefly containing quartz, sericite, kaolinite and 0.97% Fe2O3) and alumina-added (-30%) products were measured. A bending creep curve up to 3h consisted of primary and secondary steps. The creep rate (10-7-10-4s-1) in the primary step slowly decreased with increasing bending strains and then decreased rapidly in the secondary step. The mean creep rates in the primary step were obtained in the temperature range from 900 to 1050°C under stresses of 5, 10 and 20MPa. These primary creep rates decreased with alumina addition. The creep rate vs. creep stress showed linear relations on the log-log diagram, and their mean slope values were 1.26±0.27, suggesting a presence of a rate-determining step of diffusion or solution-precipitation reaction in the viscous liquid of the grain boundary. The amount of the viscous liquid phase was estimated as 38 to 21% for the alumina additions of 0 to 30% at 985°C (temperature of the liquid phase formation) in the system K2O-Al2O3-SiO2 and its composition of the liquid was estimated 10% K2O, 11% Al2O3 and 79% SiO2. However, the added alumina almost remained without reaction. The decreasing activation energies from 450kJ⋅mol-1 to 150kJ⋅mol-1 with alumina additions up to 30% were obtained.

粒状の低品位天草陶石の水熱処理による精製

A method of hydrothermal treatment has been tested to refine low-grade Amakusa pottery stones in both size ranges from 2.36 to 4.75 and from 4.75 to 9.5mm in order to upgrade for pottery use. Hydrochloric acid, 0.14mol/l, with addition of aluminum chloride is proved effective to alter albite into kaolin mineral under the hydrothermal condition at 200°C. This improves in the refractoriness of the treated samples as much as the same grade of the common high-grade Amakusa pottery stone. The treatment contributes to whiteness by decreasing Fe2O3 content of the products.

High Mechanical Strength Porcelain Body Prepared from Amakusa Pottery Stone Containing Soda Feldspar

Amakusa low refractory potterystone contains a certain amounts of soda feldspar, so have not been used as raw materials of porcelain body. Effects of grinding on manufacturing porcelain body from the potterystone were examined. With increase in grinding time, vitrification of the bodies and dissolution of quartz grains were promoted, their closed pores became smaller, and their bending strength became larger from at lower temperatures. In this experimental conditions, high bending strength as 1850kgf/cm2 was obtained with body prepared from the pottery stone ground for 103h, and fired at lower temperature as 1100°C. Bending strength of fired bodies increased with the increase in their bulk density and quartz content up to 20-30%, but had not any relations with their mullite content. The strength also increased with increase of d211 of quartz, which means that the compression prestress of glassy phase surrounding the quartz grains have considerable effects on the strength of the porcelain body.

天草陶石に含まれるセリサイトの粘土浮選に及ぼす影響 天草陶石の脱長石浮選に関する研究 （第３報）

The effect of sericite property on clay flotation of Amakusa pottery stones with Coco amine hydrochloride (COAC) as a collector was examined for the samples collected from different quarries. The clay minerals of Amakusa pottery stones are mainly sericite and a little amount of kaolinite. Results obtained are summarized as follows.1) When sericite in Amakusa pottery stones was treated with dodecylamine hydrochloride (DAC) which is the main component of the collector, dodecylamine-sericite complex was formed in the interlayers of sericite. The formation ratio of dodecylamine-sericite complex increased with the increase of the ratio of swelling layers (montmorillonite) in sericite.2) The flotation recovery of clay minerals was low, since the amount of COAC adsorption on the external surface of clay minerals was little due to the large amount of COAC adsorption in the interlayers of sericite with the swelling layers.3) With increasing the ratio of the swelling layers in sericite, the amount of DAC adsorption increased and the flotation recovery of clay minerals decreased.

Rheological Properties of Sericite Suspensions

Shear stress of sericite suspensions was measured against shear rate in the range of 16 to 650s-1 using a rotational viscometer. Mineral compositions of two kinds of clay particles (AT-S, AT-K), which were obtained by elutriation from two different kinds of powdered Amakusa pottery stones, were mainly sericite and a few amount of kaolin mineral and quartz. Rheological properties of these sericite suspensions were approximated as Bingham body and analysed using DLVO theory of coagulation and dispersion. The results were summarized as follows;(1) Bingham yield stress (BYS) values obtained from the relation between shear stress and shear rate became higher with increasing the volume fractions of AT-S and AT-K suspensions from 1.8% to 6.9%. BYS values of two suspensions were nearly zero at pH 7, increased from pH 6 to pH 5, and decreased at pH 4.(2) Total potential energy of interaction between two flat clay particles and Bingham yield stress (BYS) of clay suspensions were calculated using the estimated edge and face potentials of sericite on the basis of DLVO theory and the equation of total energy dissipation rate. The calculated results showed that BYS values of both sericite suspensions became zero at pH 7, then had finite values at pH 6 and pH 4, and had a maximum at pH 5 because these calculated values were brought about from the different association modes such as face to edge and edge to edge. These changes of calculated BYS values with pH explained well those of measured ones. It was also made clear that the thickness of sericite gave a great effect on BYS values.

Refinement of the Low-Grade Amakusa Pottery Stone by Hydrothermal Treatment

The major mineral compositions of Amakusa pottery stone are quartz, sericite and kaolin mineral. The refinement of the low-grade of Amakusa pottery stone has been required because of the recent shortage of the resources of high-grade one. This paper concerns an optimum hydrothermal condition to refine the low-grade Amakusa pottery stone of which impurities are feldspar, limonite, siderite and calcite. The results obtained are as follows:(1) Feldspar included in the sample is converted into kaolin mineral with 0.5wt% HCl solution at the temperature below 200°C and about 15atm. The formation of kaolin mineral is observed to be increased with increases in volume of the solution, temperature, and the treatment time.(2) Conversion of the feldspar into the kaolin mineral is promorted by adding aluminium chloride under the condition concerned. At the temperature lower than 180°C, no formation of kaolin mineral is observed. Aluminum chloride is considered to supply the insufficient alumium during the conversion of feldspar to kaolin mineral.(3) A product having SK value higher than 26 and Fe2O3 content lower than 0.4wt% is obtained from a raw material with SK value less than 15 by the hydrothermal treatment.(4) A plasticity index of a product is measured with the Pfefferkorn method to be higher than that of a raw material.(5) The refined pottery stone obtained in the present study has smaller green strength and higher firing shrinkage than those of common Amakusa pottery clay. This is considered to be due to the difference of its surface state from that of a raw material.

On Quartz in Amakusa Pottery Stone

On Quartz in Amakusa Pottery Stone

天草陶石の脱長石浮選に関する研究 （第２報） 天草陶石の連続式浮選試験とその速度論的考察

Following in the first report which elucidated that feldspar (albite) was effectively removed from low grade Amakusa pottery clay by two-stage flotation in laboratory batch-test, continuous flotation has been applied to the process. The results are as follows:1) The semi-batch tests, which were carried out before continuous flotation tests, indicated that each mineral was devided into two groups having the slow and fast flotation rates.2) In the rougher stage of continuous clay flotation, concentrations of collector were higher than the values expected from the semi-batch tests and tailing flow rate of pulp remarkably decreased owing to discharge of froth. As a result, the residual mass ratios showed lower than the simulated value on the basis of the results of semi-batch tests.3) In feldspar flotation, the residual mass ratios agreed well with the simulated ones because tailing flow rate of pulp did not decrease so much and the concentrations of collector were almost consistent with the ones in the semi-batch test.4) The refractoriness of the products obtained by the continuous flotation was improved. It was verified that the continuous flotation process for the removal of feldspar from the low grade Amakusa pottery stone is technically feasible.

Constituent Minerals of Amakusa Pottery Stones

Constituent Minerals of Amakusa Pottery Stones

Cell dimensions, minor element composition and high-low inversion of quartz in the Amakusa pottery stone.

Quartz is the predominant constituent of the Amakusa pottery stone together with sericite and kaolin minerals. The quartz grains are 10–60 μm in size and show undulatory extinction under the microscope. X-ray diffraction, electron microprobe, and differential thermal analyses have revealed the following properties of the quartz.X-ray diffraction peaks of the quartz are broad. The cell dimensions are relatively large with a=4.9137–4.9155 A and c=5.4047–5.4057 A at 21°C. Most quartz samples show relatively high Al2O3 contents around 0.1 up to 1 wt% in maximum, and are inhomogeneous in the Al2O3 content among quartz grains. The high-low inversion peak in the DTA curve is broad and the peak temperature is by 2–12°C lower than that of ordinary quartz.Thus the quartz in the Amakusa pottery stone is characterized by the large cell dimensions, the high Al content, the low temperature of the high-low inversion, the relatively low crystallinity and some inhomogeneity.

天草陶石からの陶土製造のための新粉砕システムの開発

This paper deals mainly with the particle size distribution of pottery clays on the market and the ways of grinding using Amakusa pottery stones which are raw materials for Arita porcelain.The conclusions obtained are summarized as follows:1. It is elucidated from a statistical analysis that the pottery clays on the market being prepared by stamp mill grinding and elutriation have particle size distributions obeying the Gaudin-Schuhmann distribution, irrespective of whether they are pottery clays for throwing or casting.2. A new grinding system is proposed in which a pottery stone is ground by a roller mill and successively by a stamp mill for a period of 90 minutes. It is found that a pottery powder prepared using such a method has almost the same properties as pottery clays on the market with respect to particle size distribution and mineral composition and also has enough of the properties needed to actually make Arita porcelain.

Relation between Predicted Refractoriness by Thermal Expansion Curves of Amakusa Pottery Stone and its Mineral Compositions

Refractoriness and mineral compositions of various kinds of Amakusa pottery stones (218 samples) were measured by thermal expansion and X-ray powder diffraction methods respectively. The nominal temperature (Tsk) equivalent to refractoriness was predicted by thermal expansion curves. The mineral compositions were determined on the basis of X-ray powder profile refinement method. The statistics of data for Tsk (°C) and mineral compositions, such as quartz (QU (wt%)), sericite (SE (wt%)), kaolin (KA (wt%)), albite (AB (wt%)), calcite (CA (wt%)), siderite (SI (wt%)), showed a high correlation between them with the correlation coefficient of 0.981, which was expressed by Tsk=1404+2.98QU+0.00SE+1.72KA-3.20AB-23.2CA-24.4SI.

Clay Minerals in the Amakusa Pottery Stones and Some Features of Their Pottery Clays.(II)

Clay Minerals in the Amakusa Pottery Stones and Some Features of Their Pottery Clays.(II)

2段階浮選による天草陶石の脱長石

2段階浮選による天草陶石の脱長石

Determination of Refractoriness of Amakusa Pottery Stone by Thermal Expansion Curves

Determination of Refractoriness of Amakusa Pottery Stone by Thermal Expansion Curves