Ceramic porcelain stoneware production with Spanish clays purified by means of the removal of iron compounds and organic matter using physical methods

Abstract

As the production of ceramic porcelain stoneware in Spain is totally conditioned by the importation of ball clays, because of the lack of adequate Spanish ball clays, this work has focused on the formulation of ceramic porcelain body from Spanish clays purified by means of physical removal processes. This method was applied to three Spanish clays containing common clay impurities of iron (hematite and siderite) and organic matter. Iron removal was carried out using the wet sieve method, the hydrocycloning method and the electromagnetic filtering method, obtaining a reduction in iron content of up to 80 wt%, while the clay containing organic matter was treated thermally at 400ºC for 30 minutes so as to leave it almost completely purified. These treated clays, after being characterized (chemical and mineralogical composition, plasticity, organic carbon, thermal behaviour and colour), were used in the porcelain stoneware body composition instead of imported clays, the result being a composition capable of substituting the standard porcelain stoneware formulation in terms of sintering, morphology, colour, flexural strength and dilatometry.

Mineralogical and Thermal Characterization of Kaolinitic Clays from Terra Alta (Catalonia, Spain)

“…Most of the analyzed samples from the outcrops can be classified as silico-aluminous clays. This chemical composition is similar to other kaolins with applications in the ceramics industry [25][26][27][28][29][30][31] (Figure 3). [25], Turkey I [26], Turkey II [27], Tunisia I [28], Tunisia II [29], Castellón (Spain) [30], Western Portugal [31].…”

“…This chemical composition is similar to other kaolins with applications in the ceramics industry [25][26][27][28][29][30][31] (Figure 3). [25], Turkey I [26], Turkey II [27], Tunisia I [28], Tunisia II [29], Castellón (Spain) [30], Western Portugal [31]. [25], Turkey I [26], Turkey II [27], Tunisia I [28], Tunisia II [29], Castellón (Spain) [30], Western Portugal [31].…”

“…Minor components are TiO 2 , K 2 O, CaO, P 2 O 5 and MgO, with values below 1 wt %.Most of the analyzed samples from the outcrops can be classified as silico-aluminous clays. This chemical composition is similar to other kaolins with applications in the ceramics industry[25][26][27][28][29][30][31] (Figure 3).…”

“…[25], Turkey I [26], Turkey II [27], Tunisia I [28], Tunisia II [29], Castellón (Spain) [30], Western Portugal [31]. [25], Turkey I [26], Turkey II [27], Tunisia I [28], Tunisia II [29], Castellón (Spain) [30], Western Portugal [31].…”

Characterization of Brazilian Northeastern plastic clays

“…A characteristic commonly required for ball clays is the presence of low amount of coloring oxides, such as Fe 2 O 3 and TiO 2 . Literature indicates that clays used in porcelain tile formulations should have Fe 2 O 3 <1% [6,29], however a limit of 3% of Fe 2 O 3 in ball clays used for the production of light-firing bodies, such as sanitary ware, is overall accepted [19]. High amount of Fe 2 O 3 can cause ceramic body deformation [30], incorporation of iron ions in the glassy phase and/or in the crystalline phases, and the development of dark-firing bodies.…”