Characterization of clays from the Foumban region (west Cameroon) and evaluation for refractory brick manufacture

Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 447-457
Author(s):  
A. Pountouenchi ◽  
D. Njoya ◽  
A. Njoya ◽  
D. Rabibisao ◽  
J.R. Mache ◽  
...  

ABSTRACTThree clayey materials named MY3, KK and KG originating from the Foumban region (west Cameroon) were analysed to determine their granulometry, plasticity, major-element chemistry and mineralogy. Dilatometric and ceramic behaviour were also investigated. Clays were shaped by uniaxial pressing in a steel mould. Shaped samples were heated at 1300, 1400 and 1500°C. The end products were characterized in terms of their density, porosity and compressive strength. Raw materials differ in terms of their mineralogical composition, grain-size distribution, Al2O3 content and the nature and abundance of impurities inducing specific thermal behaviour during dilatometric analysis and sintering tests. The final material properties may be related to the main features of the raw materials used.

Cerâmica ◽  
2019 ◽  
Vol 65 (376) ◽  
pp. 578-584
Author(s):  
A. Laursen ◽  
L. N. L. Santana ◽  
R. R. Menezes

Abstract Plastic clays are one of the main raw materials used in ceramic technology. However, there is a shortage of good quality plastic clays in the world for use in porcelain technology. The aim of this study was to characterize plastic clays from Northeastern Brazil. Chemical and mineralogical composition, particle size distribution, plasticity and green strength of the clays were determined. The analyzed clays were predominantly composed of kaolinite and quartz, and some contained smectite. The amount of iron oxide in the clays was higher than 1.0% and for some of them the values were higher than 3%; the liquid and plastic limits ranged from 22% to 48% and 10% to 32%, respectively. According to characterization data, three plastic clays had potential to be used as alternative ball clay, due to their plasticity and mineralogical characteristics.


2012 ◽  
Vol 727-728 ◽  
pp. 844-849 ◽  
Author(s):  
Tércio G. Machado ◽  
Uilame Umbelino Gomes ◽  
Flanelson M. Monteiro ◽  
Samara M. Valcacer ◽  
Gilson G. da Silva

The scheelite occurs mainly in northeastern Brazil, with highest abundance in the states of Rio Grande do Norte and Paraíba - Scheelite Seridó Province. Mining is considered an activity that provides a high environmental degradation due to the large amount of minerals and waste involved. Most mining companies have no technologies or processes that allow the recycling of mineral waste generated. The aim of this study is to evaluate the influence of different percentages of reject on the mechanical properties of scheelite and aesthetic (staining of the final product after firing) of the clay of the city of Boa Saúde - RN. The raw materials used were characterized by XRD, XRF and particle size analysis. Assay was performed by water absorption, linear retraction and bending tests on three points for the characterization of the final product. The raw materials used were from the city of Currais Novos-RN.


Clay Minerals ◽  
2010 ◽  
Vol 45 (2) ◽  
pp. 229-240 ◽  
Author(s):  
M. Rebelo ◽  
F. Rocha ◽  
E. Ferreira Da Silva

AbstractThe use of pelitic geological materials for the treatment of muscle-bone-skin pathologies, by application of a cataplasm made of clay and mineral water mixture, is currently receiving attention and interest from the general public and scientific community. In Portugal there are several natural occurrences of clays/muds which are used for pelotherapy and/or geotherapy. These are carried out either indoors (thalassotherapy and thermal centres) or outdoors, in natural sites generally located near the seaside. The aim of this study is to assess the mineralogical and physicochemical properties of Portuguese raw materials for therapeutic purposes. These materials were collected from different Portuguese Mesozoic-Cenozoic geological formations located in the neighbourhood of thermal centres or at beaches known from their empirical applications. X-ray diffraction (XRD) and scanning electron microscopy (SEM-EDS) were used to assess the mineralogical composition of these clays. Physicochemical properties, such as specific surface area, cation exchange capacity, plasticity/abrasiveness indices and heat diffusiveness were also determined. Having distinct geological ages and genesis, the materials examined are mainly illitic. Less abundant kaolinite and smectite are also present. With respect to their physicochemical properties, all samples have good thermal properties which make them potentially suitable for therapeutic or aesthetic purposes.


2015 ◽  
Vol 30 (2) ◽  
pp. 122-129 ◽  
Author(s):  
Giovanni Cavallo ◽  
Maria Pia Riccardi ◽  
Roberto Zorzin

A first attempt to differentiate goethite- and hematite-based natural materials, used for several purposes during the Late Palaeolithic in the Lessini Mountains (Italy), is here proposed. All raw materials were collected from known geological sites within a distance of about 20 km from archaeological excavations (Tagliente and Fumane caves) where ochre fragments were found. X-ray powder diffraction allowed the mineralogical composition of samples collected from carbonate and volcanic geological host and parent rocks to be inferred; in addition, a preliminary distinction based on the different mineral assemblages, on the presence of distinctive mineral phases and on the degree of crystallinity of some compounds such as hematite, became possible. The acquired data thus represent a sort of preliminary inventory for provenance studies on archaeological samples originating in the same region, for which ancillary micro-analytical and geochemical techniques are planned.


2018 ◽  
Vol 23 (1) ◽  
pp. 163-177 ◽  
Author(s):  
Anna Rauba-Bukowska

Abstract For microscopic examination, 22 pottery fragments from sites 11, 15 and 20 in Święte, Jarosław District were selected. The pottery types included beakers (N=19) and amphorae (N=3). The goal of the petrographic analysis was to identify mineralogical composition of ceramic fabric, sources of raw materials, and intentional additives to the clay. The analysis yielded data that helped determine ceramic fabrics types and preparation methods, as well as pottery firing conditions and approximate firing temperature. In all samples analysed, ceramic fabrics were prepared in a similar way, using heavy clay poor in muscovite, with grog deliberately added. Crystalline material present in some of the samples is most likely a natural component of raw materials used in the production process. No sand is added to the clay. No other method for preparing pastes was identified for the amphorae type. Previous observations on amphorae firing are confirmed: amphorae are fired in oxidizing conditions. The ceramic fabrics of two vessels have a deliberate admixture of bones in addition to grog and argillaceous rock intraclasts. Vessels decorated with cord impressions and vessels with herringbone or other incised patterns are more often made from paste type A (inclusion and grog) and paste type B (grog), respectively.


2012 ◽  
Vol 65 (4) ◽  
pp. 513-521
Author(s):  
José Manuel Rivas Mercury ◽  
Gricirene Sousa Correia ◽  
Nazaré Socorro Lemos Silva Vasconcelos ◽  
Aluísio Alves Cabral Jr. ◽  
Rômulo Simões Angélica

This work involved the characterization of clays collected in the municipalities of São Luis, Rosário, Pinheiro and Mirinzal (state of Maranhão, Brazil), based on specific mass, specific surface area, cation exchange capacity (CEC), particle size distribution, X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TG-DTA) and Atterberg limits. Technological tests for ceramic applications were also carried out on compacts pressed under 20 MPa and heat-treated at 850, 950, 1050, 1150 and 1250ºC. Our results indicated that two of the clays composed of kaolinite, quartz, and anatase with high plasticity limits, have excellent properties and can be used in the whiteware industry. The other ones are red-firing clays and have a mineralogical composition of quartz, kaolin, feldspar, montmorillonite, hematite and goethite. The latter showed low and moderate values of plasticity, which makes them suitable for the production of heavy clay products.


2013 ◽  
Vol 66 (1) ◽  
pp. 91-98 ◽  
Author(s):  
José Manuel Rivas Mercury ◽  
Domingos de Jesus Costa Pereira ◽  
Nazaré do Socorro Lemos Silva Vasconcelos ◽  
Aluísio Alves Cabral Jr. ◽  
Romulo Simões Angélica

This work involved the first-ever characterization of antique Portuguese ceramic wall tiles in the Historic Center of São Luis do Maranhão, Brazil. The tiles were characterized by optical microscopy, X-ray diffraction (XRD) and chemical analysis to identify the possible raw materials used in the fabrication process, as well as the firing temperature of these materials. The results indicate that the microstructure of these materials consists of pores of varying sizes with calcite incrustations and quartz grain sizes smaller than 500 µm distributed in a pinkish yellow matrix, which were identified by XRD as calcite, gehlenite, wollastonite, quartz, and amorphous mineral phases. Based on this information, it can be inferred that the original raw materials probably consisted of a mixture of kaolinitic clays (Al2O3·2SiO2·2H2O) rich in calcium carbonates and quartz, or mixtures of kaolinitic clays, quartz and calcite, which did not reach the pre-firing temperature of 950ºC.


1964 ◽  
Vol 30 ◽  
pp. 111-133 ◽  
Author(s):  
J. R. Cann ◽  
Colin Renfrew

Evidence of contact between cultural groups is of great importance to the study of prehistory. Although the development of absolute dating methods has decreased our dependence on the discovery of such contacts for chronology, they are essential material when the origin and spread of culture is being studied. In the past, cultural contacts have generally been demonstrated by typological similarities of artifacts, but unfortunately many typological comparisons are open to discussion, and it can be exceedingly difficult to be certain of direct contact by this means alone.The importance in this respect of the study of raw materials used in places far from their place of origin and presumably deliberately imported has long been realized. Recently more attention has been paid to the careful characterization of such materials; the detection, that is, of properties of the specimen under study which are characteristic of material from particular sources. By this means it is often possible to assign a source to a given specimen. The petrological identification of British neolithic stone axes is perhaps the most comprehensive archaeological characterization study yet undertaken. Demonstrations of trading links made by such methods, if based on a sure identification and a comprehensive survey of possible sources, are not open to the criticism and doubt which may be directed at typological similarities. The variety of techniques now available for the analysis and identification of materials makes this field a promising one for the archaeologist.


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