Kaolin Residue Research Articles

Effect of dry grinding on the physicochemical properties of silica materials prepared from kaolin residue

The present study evaluates the effect of dry grinding on the physicochemical properties of silica materials prepared from kaolin residue. The kaolin residue was ground at varying times and then treated with sulfuric acid (20 mass%) at 100 °C for 2 h. X-ray diffraction, scanning electron microscopy, Fourier transformation infrared spectroscopy, and N 2 adsorption techniques were used to examine the effect of grinding on the raw materials and products. The SiO 2 content was also analyzed to compare with the raw materials. The degree of amorphization calculated from X-ray diffraction (XRD) data of silica increased with grinding time. The band intensities of Si O Al and Al OH were decreased by the grinding process, which was beneficial to the subsequent leaching. Morphologic and structural studies revealed that the crystalline structure of kaolin residue was destroyed during grinding. The SiO 2 content of ground leached samples varied with grinding time, and the maximum value was above 92%. Grinding caused the surface area of the silica to increase to 167.84 m 2/g, but decrease with longer grinding time. The formation of micropores contributed to the increase of the surface area. Structural breakdown by grinding is considered as the main reason for the enhancement of leaching behavior and improvement of the SiO 2 content and porous properties.

Use of Microwave Energy for Obtaining the Mullite

The kaolin beneficiation industries produce waste that is rich in Al2O3 and SiO2, oxides that when sintered at high temperatures react to form mullite. Due to the rare occurrence of the mullite mineral in nature, the number of studies in order to obtain it has been growing in recent years due to its properties excellent. This study aims to examine the feasibility of the use of microwave energy as an alternative to synthesize mullite from kaolin residue, since the use of microwave energy in the synthesis of materials has gained importance for the speed and economy when compared to conventional methods. The compositions studied (residual kaolin + alumina) were established according to the stoichiometry of mullite. The samples were sintered in a microwave oven home changed, varying power and time. It was observed that with the increase of these variables the intensity of the peaks of the mullite phase increased.

Effect of mechanical activation on acid-leaching of kaolin residue

The effect of mechanical activation on leaching of a kaolin residue in hydrochloric acid (20 mass %) was investigated. The influence of mechanical activation on morphology and particle size was studied by scanning electron microscopy (SEM) and particle size analysis. The SEM images demonstrated that mechanical activation induced the transformation of the kaolin residue from needle-shaped particles to spherical particles. The particle size decreased. The XRD reflections of the raw residue disappeared after 4 h of mechanical activation. Thus, mechanical activation improved the acid leaching by changing the physicochemical properties of the residue. The apparent activation energies for leaching of the unground and ground residues were calculated to be about 43 kJ/mol and 24 kJ/mol, indicating that the leaching process of the unground residue was controlled by the surface chemical reaction and the ground residue was controlled by a diffusion process. Mechanical activation greatly improved the activity of the kaolin residue and affected the leaching kinetics, which reduced leaching temperature and leaching time.

Sprayer type and water volume influence pesticide deposition and control of insect pests and diseases in juice grapes

In a mature Vitis labrusca L. “Niagara” vineyard, we compared an airblast sprayer and an air-assisted rotary atomizer (AARA) low-volume sprayer for coverage of grape clusters and control of grape berry moth, Paralobesia viteana. In addition, the effect of spray volume on control of fungal diseases was evaluated using the fungicides ziram and azoxystrobin applied with an airblast sprayer. For evaluation of coverage, sprayers applied kaolin clay at 28 kg/ha to grapevines while operating at low, medium and high water volumes. Kaolin residues on grape clusters were analyzed to compare the total amount of spray material deposited, percent of fruit surface covered, number of deposits, size of deposits and distance between deposits. There were no significant differences between sprayers or water volumes in the total amount of kaolin deposited on clusters, but the percent surface coverage was much greater on outside-facing berry surfaces (facing the sprayer) than inside-facing surfaces (facing the rachis). On the outside-facing berry surfaces, the airblast sprayer at 468 L/ha of water (medium volume) provided the highest percent coverage, the greatest density of deposits, the largest deposit diameter, and the smallest distance between deposits. On the inside-facing berry surfaces, the same sprayer–volume combination provided the highest percent coverage and greatest deposit diameter, but deposits from the airblast sprayer operating at 935 L/ha (high volume) had the smallest distance between deposits. No significant differences between sprayers or among water volumes were detected in the deposit density on the inside-facing berry surfaces. Bioassays of grape clusters sprayed with fenpropathrin or methoxyfenozide using the airblast or AARA sprayers at two water volumes revealed the greatest fruit protection from P. viteana at the higher volume for the airblast sprayer, but at the lower volume for the AARA sprayer. Spray volume of the airblast sprayer also affected disease control by the protectant fungicide ziram more than by the systemic fungicide azoxystrobin, with 468 L/ha providing better control than 187 L/ha. However, for most diseases, fungicide type was more influential than spray volume in determining the disease control outcome. The results of this study emphasize the need for appropriate water volumes relative to the sprayer and pesticide being used to optimize pest and disease control in juice grape vineyards.

Gas Exchange of Apple and Blackberry Leaves Treated with a Kaolin Particle Film on Adaxial, Abaxial, or Both Leaf Surfaces

Kaolin particle films are used as a means of pest control in some commercial apple orchards in the Maritime provinces; however, no studies to date have evaluated the impact of these particle films on leaf gas exchange under the region's growing conditions. Also previously unexplored is the gas exchange response of blackberry leaves to kaolin particle films and the question of whether leaf gas exchange response varies according to the leaf surface of particle film application. A study consisting of an apple field trial and a blackberry greenhouse trial was conducted during the 2005 growing season in Bouctouche, New Brunswick, Canada, with the aims of 1) characterizing the leaf temperature and gas exchange responses [net photosynthesis, stomatal conductance (g s), intercellular CO2, and transpiration] of ‘Ginger Gold’ apple [Malus ×sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] leaves to a kaolin particle film (95% kaolin clay) applied at various leaf residue densities under the province's growing conditions, 2) characterizing the leaf temperature and gas exchange responses of ‘Triple Crown’ blackberry (Rubus L. subgenus Rubus Watson) leaves to treatment of adaxial or abaxial surfaces with the kaolin particle film at various leaf residue densities, and 3) determining whether the gas exchange response of apple and blackberry leaves to the kaolin particle film varies according to leaf temperature. Leaf gas exchange measurements were taken under conditions of ambient CO2, saturated light, moderate (apple) or high (blackberry) relative humidity levels and leaf temperatures ranging from 26 to 39 °C (apple) and 15 to 41 °C (blackberry). When the particle film was applied to both the adaxial and abaxial surfaces of apple leaves at kaolin residue densities of 0.5 to 3.7 g·m−2, leaf temperature was reduced by up to 1.1 °C (P = 0.005) and g s was increased (P = 0.029) relative to leaves with trace (<0.5 g·m−2) levels of kaolin deposits. No other effects of kaolin leaf residue density on apple leaf gas exchange were found, nor were any interactions of leaf temperature × residue level (P > 0.05). When applied to a fixed area on the adaxial or abaxial surfaces of blackberry leaves at kaolin residue densities of 0.5 to 10.8 g·m−2, the particle film did not alter leaf temperature or gas exchange (P > 0.05). No interactions of leaf temperature × residue level or leaf temperature × leaf surface × residue level were found to affect blackberry leaf gas exchange (P > 0.05).

The Use of Granite and Kaolin Residues as Raw Materials to Obtain Ceramic Tile

Recycling of residues from different industrial process as new raw materials has been studied by several institutions to be applied in the production of ceramic bricks, roof tile. The aim of this work is to study the potentiality of the residues from granite and kaolin industries as raw materials to obtain ceramic tile. The raw materials were fired at temperatures of 1100oC, 1120oC and 1150oC. After fired the specimens were submitted to a physical and mechanical tests, such as, linear shrinkage, mechanical resistance, water absorption and apparent density. The results show that the residues can be used in the composition of the paste to produce ceramic tiles.

Mullite Preparation from Kaolin Residue

In the process of kaolin improvement to types of residue are generated and dispose in the environment. The first residue, about 70%wt, generated from the washing of the kaolin and the second generated residue from the improvement in sieve 200 mesh (0.074mm), of the remaining of the washed kaolin 30%. These residues can present excellent qualities to be used as raw materials rich in kaolinite. Kaolinite when is submitted to heat give two stable phases: mullite and crystobalite. The properties of mullite, such as, low thermal expansion, low dielectric constant and high mechanical resistance, make this material as a good candidate to be applied in electronic products and in structural high temperature uses. In this work, compositions with residue from kaolin, alumina and ball-clay were studied to obtain mullite. The compositions were established starting from proportion between silica and alumina to obtain mullite (2SiO 2 .3Al 2 O 3 ). The samples were made by pressing processing with 27 MPa and sintering at temperatures of 1350 and 1500°C, with heating rate of 10°C/min. Through the results from chemical analysis of the formulated masses, it can be verified that the proportions of the oxides were close to the stoichiometric of the mullite and that the sintering, at studied temperatures, give the formation of mullite, and confirmed by the DRX analysis. The preliminary results showed that the compositions with low alumina content and submitted to a high temperatures, presented the best results.

The manufacture of bricks from semiacid materials by semidry pressing

Tests in laboratory and industrial conditions showed the possibility of producing semiacid refractories by the semidry pressing method using Prosyanov kaolin and quartz residues from its enrichment in the batch.