Zircon Sand Research Articles

The Use of Local Raw Materials for the Manufacturing of Import Substitution Casting Products on Investment Casting Technology

The use of local raw materials for the manufacturing of import substitution casting products on investment casting technology has been done. Compared to the conventional casting process, investment casting has the advantage of being able to create a sophisticated casting product and produce a product that is near net shape, so it is no need machining process. The objective is as an effort to find an alternative method of making a quality casting product, has high added value with the utilization of local raw materials which available in Indonesia so that it can reduce the cost of production and dependence on imports of industrial raw materials which are very expensive in the investment casting process. The method of making casting products with investment casting process, including: pattern making, mould making, dewaxing, melting, pouring, finishing and testing. Investment casting technology has been successfully applied to the manufacture of rocker arm, impeller pump and turbine blade with the utilization of local raw materials ie: epoxy resin as a substitute for metal pattern, mixture wax of paraffin, and celo resin for the pattern of wax and zircon sand of Bangka island as coating slurry for ceramic mould. The discussion of this paper is expected to be a case of developing other casting products needed by Indonesia for industry such as: medical equipment, agricultural equipment, textile equipment, gun and small armaments, electronics, automotive and electrical components etc.

Performance of digital patternless freeze-casting sand mould

Digital patternless freeze-casting technology is a new approach for obtaining frozen sand moulds using digital milling technology. The change law of tensile strength and air permeability of frozen sand moulds (100-mesh and 200-mesh silica sand, and zircon sand moulds) under different freezing temperatures and water contents was studied. Results show that with the decrease of freezing temperature and the increase of water contents, the tensile strength and air permeability of the sand moulds are gradually improved. Meanwhile, computed tomography technology was used to characterize the shape and size of the water film between the sand particles mixed with 4wt.% water. The results show that in silica sand moulds, the form of water film is lumpy, and 200-mesh silica sand moulds have more water films and higher proportion of small-sized water films than 100-mesh silica sand moulds, while in zircon sand moulds, the form of water film is membranous. At the same freezing temperature and water content, the tensile strength of zircon sand mould is the highest, and 100-mesh silica sand mould is the lowest. A comparative solidification experiment of A356 aluminum alloy was carried out in frozen sand mould and resin sand mould. The results show that the primary α-Al phase appears in the form of equiaxed and eutectic silicon phase is needle-like in freezing sand mould casting, but the primary α-Al phase grows in the form of dendrites, and the eutectic silicon phase is coarse needle-like in the resin sand mould casting. The difference of microstructure is caused by the different cooling rate. The cooling rate of A356 aluminum alloy in frozen sand mould is higher than that in resin sand mould.

Influence of Kaolin and Silica on some Refractory Properties of Pingell, Zircon Sand

100kg of zircon sand raw material was obtained from Pingell, Toro Local Area of Bauchi State while silica and kaolin were used as the additive materials in different proportions. The materials as received were wet and in large chunks, and was sun dried prior to crushing with Jaw crusher and sieved with the sieve of size 100 µ to obtain fine powder particles. Samples of various compositions were prepared from the powder particles of Zircon sand (X); Zircon sand and silica (Y); zircon sand, silica and kaolin (Z) and mixed together based on the experiment’s program with a predetermined amount of water in the mixer. Refractory brick test specimens were prepared by standard methods from samples A, B and C and subjected to refractory test such as apparent porosity, bulk density, cold crushing strength, linear shrinkage, thermal shock and refractoriness in order to evaluate the effects of adding silica and gypsum to Pingell zircon sand and investigate its suitability as raw material for refractory brick production and furnace linings. From the result obtained, the average porosity of X, Y and Z is 13.5, 18.3 and 21.6 % respectively while the respective bulk density are 3.2, 2.0 and 1.8 g/cm3. The values of the cold crushing strength for samples X, Y and Z are respectively 25.5, 23.4 and 18.8 MN/m2 but the firing shrinkage is 4.5, 5, and 6.5 %. Thermal shock resistance of 26, 20 and 22 cycles were obtained respectively for X, Y and Z. Refractoriness of 1600, 1580 and 1610 0C were obtained respectively for samples X, Y and Z. The porosity, firing shrinkage and refractoriness increased with increase in the addition of silica and kaolin to zircon sand whereas the bulk density, thermal shock resistance and cold crushing strength of zircon sand decreased with the addition of silica and kaolin but the addition of silica reduced the refractoriness of the zircon sand. The addition of silica and kaolin in the appropriate proportions improved the refractory properties of the zircon sand and hence will find applications in the production of refractory bricks and furnace lining.

Study of the Synthesis of Zirconia Powder from Zircon Sand obtained from Zircon Minerals Malaysia by Caustic Fusion Method

The zircon powder from Zircon Minerals Malaysia is a pure premium grade zircon sand milled 1.5 µm that contain ZrSiO4, ZrO2, HfO2, SiO2, Al2O3, TiO2, and Fe2O3. The monoclinic zirconia powders were synthesized from the zircon sand of Zircon Minerals Malaysia, by caustic fusion method at calcination temperatures between 500 °C to 800 °C. The as-synthesized zirconia was characterized through X-Ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential thermal analysis (TG-DTA), and X-Ray fluorescence (XRF) techniques. The XRD results show two monoclinic phases of microcrystalline zirconia. Zirconia that was calcined at 600 °C obtained the highest value of ZrO2, which was 54.48%; followed by zirconia calcined at 700 °C, 800 °C, and 500 °C, which obtained the ZrO2 values of 53.58%, 52.41%, and 51.53%, respectively, based on the XRF analysis. As-synthesized zirconia showed monoclinic phases where the surface areas were 0.0635 m2/g, 0.135 m2/g, 0.0268 m2/g, and 0.0288 m2/g, for zirconia calcined at temperatures of 500 °C, 600 °C, 700 °C, and 800 °C, respectively. The surface structure of the powder that had been calcined at 600 C showed similarities with the commercial zirconia. The similarities of the synthesized zirconia and commercial zirconia showed that the zirconia powder could be synthesized using zircon sand by caustic fusion method, even though the content of zirconia was lower compared to that of the commercial zirconia powder.

Anti fouling coating characterization with purified Zirconia from West Kalimantan Zircon Sand for Boiler application

Zircon sand is a mineral material for zirconia purification which can be found in Indonesia. Zirconia has various functions, one of the function applied at Boiler high temperatures. The low coefficient of zircon thermal expansion indicates high thermal shock and spalling resistance. In this study, zirconia comes from Kalimantan zircon sand was applied to an anti-fouling coating. The purified zirconia is compared with zircon sand and synthetic zirconia. The purified zirconia yields a 82.48% Zr content, compared to the zircon sand has 70.85% Zr content and 89.43% in synthetic zirconia. The substrate used for coating is ferritic steel. The coating method uses a brush coating then sintered at a temperature of 400°C and 800°C. Coatings that contained purified zirconia have a rougher surface compared to coatings that contained zircon sand and synthetic zirconia. It is because the zirconia powder granules produced have a larger size. The microstructure also shows the surface of the coating with zirconia from the purification has a tenuous structure with large granules. It shows further treatment is needed in the purification of zirconia so that the grain size is homogeneous when applied to the coating.

Kinetics of Yttrium Dissolution from Alkaline Fusion on Zircon Tailings

We studied yttrium extraction from untreated zircon sand processing waste tailings. Xenotime mineral as the rare earth element source with an abundance of yttrium (REY) was detected in sufficient grade for extraction. As much as 9.03% yttrium exists in zircon tailings (analysed by X-ray fluorescence spectrometry). The presence of yttrium was confirmed by X-ray diffractometry in xenotime minerals, which are yttrium carriers (Y-PO4). The purpose of this research was to determine the effect of leaching conditions on yttrium recovery from zircon sand after alkaline fusion treatment. Alkaline fusion was chosen to decompose phosphate into hydroxide in the xenotime mineral, which will reduce further required hydrometallurgical processing. Alkaline fusion was carried out for 3 h at 450 °C, with a ratio of sodium hydroxide to zircon tailings sand of ~ 1:1. The alkaline fusion product was leached with water, followed by hydrochloric acid treatment to leach the yttrium. Yttrium recovery reached 87% under optimum conditions (60 °C, 1 M HCl, and solid-to-liquid ratio = 1/10 for 7.5 min). A suitable model for yttrium dissolution with hydrochloric acid was diffusion through a solid particle ash layer. The calculated activation energy (EA) for this model was 20.21 kJ/mol.

Tribological properties of plasma sprayed zircon-alumina powder mixture with and without laser re-melting

ABSTRACTThis investigation focusses on the wear mechanism of as-sprayed and laser treated mullite based coatings, produced by plasma spraying, under sliding wear condition. First, an alumina powder and zircon sand mixture was plasma sprayed to produce a mullite coating. Selected as-sprayed coatings were subsequently laser treated. The tribological performances of both as-sprayed and laser re-melted coatings were assessed using a pin-on-disc wear apparatus. Hardened steel and WC-Co balls served as rubbing counterparts. A plasma sprayed alumina coating was used for bench marking purposes. Plastic deformation was the dominant wear mechanism under low load-low speed condition for both as-sprayed and laser treated coatings. However, at higher loads and speeds the coatings were found to undergo micro-fracture followed by pulverisation. Wear resistance of the coatings improved following laser treatment.

Improved Sublimation Resistance of Skutterudites by Silane Modified Ceramic-Based Coating

The organic/inorganic hybrid sol was prepared by hydrolysis polymerization of methyl-triethoxysilane (MTES) with acidic silica sol. Zirconium silicate, zircon sand and refractory fiber were respectively added to the hybrid sol to increase the stability of the coating in high temperature service. P-type skutterudite(SKD) protective coating obtained by multi-layer coating and certain pretreatment. Protective effect was studied by observing the diffusion of antimony from the SKD into the coating. The results show that the coating has the advantages of simple process and high strength and high stability after aging. The sublimation of antimony is suppressed and it is expected to be applied to the protection of SKD in vacuum.

Zirconium diboride-mullite composite form mineral: Combustion synthesis, consolidation, characterizations and properties

Zirconium diboride-mullite composite powder was synthesized in-situ by combustion in argon of a zircon sand/B2O3/Al reactant system in a 3 : 3: 10 M ratio. Zircon sand with a particle size less than 45 μm was activated by high-energy milling for 360 min. The optimum reactant system included the addition of 0.01 mol of Si. The product of the synthesis of this system contained 34 wt% ZrB2 and 50 wt% mullite. The obtained zirconium diboride-mullite powder was consolidated by hot pressing at 25 MPa in an argon environment, ramping at 10 °C/min to 1,450, 1550 and 1650 °C and holding for 60 min. The sintered composite hot-pressed at 1650 °C had a density of 3.39 g/cm3, flexural strength of 153.25 ± 1.19 MPa, hardness of 10.66 GPa and fracture toughness of 4.23 MPa.m1/2. The flexural strength and hardness of the composite was significantly influenced by the grain size of the reinforced ZrB2. The predominantly intergranular fracture observed in surface micrographs confirmed the high toughness of the composite. The coefficient of thermal expansion of the product hot-pressed at 1650 °C was 6.53 × 10−6/°C: much lower than reported coefficients of existing Al2O3, ZrO2 ZrB2, and ZrB2–SiC refractory ceramics.

MICROSTRUCTURAL ANALYSIS, MICROHARDNESS AND COMPRESSIVE BEHAVIOUR OF DUAL REINFORCED PARTICLES ADC-12 ALLOY COMPOSITE

The aim of this study was to determine the compressive properties of silicon carbide (SiC) and zircon sand (ZrSiO4) particulate reinforced with ADC-12 alloy, ADC-12 alloy composite. In this experimental study, SiC and ZrSiO4 particulates reinforced with ADC-12 alloy composite were manufactured by stir casting methods. Compressive properties of these composite materials were investigated by different weight percentages of dual reinforcement combinations (9+3) %, (6+6) %, (3+9) %wt. silicon carbide (SiC) and zircon sand (ZrSiO4)respectively, The compressive tests were conducted to determine compressive strength and young’s modulus to investigate the effects of reinforce materials on different combinations of weight percentages. The outcome of the investigations reveals that the tensile strength of composites reinforced by Zircon sand (ZrSiO4) and silicon carbide particles with a total reinforcement 12% wt, and in this hybrid reinforcement the variations (9+3) %, (6+6) %, (3+9) % were taken in to account for investigating the properties such as density, compressivestrength and hardness of the composites synthesized by Stir casting technique, also compared between each other’s. The mechanical properties evaluation reveals variations in hardness and the compressive strength values with the composite combinations. From the experimental studies, the optimum volume fraction of hybrid reinforcement in ADC-12 alloy on the basis of microstructure and mechanical properties it is found that the (6+6) wt.% combination.

Synthesis of Zirconium Oxychloride and Zirconia Low TENORM by Zircon Sand from Landak West Kalimantan

In order to enhance the added value of zircon minerals (ZrSiO4) derived from tailing gold mining in Mandor, Landak, West Kalimantan; the hydrometallurgical process is needed to obtain zirconium products such as zirconium Oxychloride (ZrOCl2.8H2O) and zirconia (ZrO2). Zirconium products that are sold must meet the requirement of Technologically Enhanced Naturally Occurring Radioactive Material (TENORM) or (ThO2 + U3O8) is below 500 ppm. The purpose of this research was to process zircon sand with TENORM content 1784 ppm to be ZrOCl2.8H2O and ZrO2 low TENORM. Zircon sand processing has been carried out through melting zircon sand with NaOH to bind Zr became Na2ZrO3 and Si as the impurities to become Na2SiO3, water leaching to separate Na2ZrO3 from Na2SiO3 and other impurities, acid leaching (HCl) to convert Na2ZrO3 to be zirconium oxychloride low Si (ZOC-1) then ZOC-1 to be zirconium sulfate base (ZBS), ZBS then being deposited to be ZrO(OH)2, ZrO(OH)2 converted to be zirconium oxychloride low TENORM (ZOC-2), ZOC-2 then being crystallized to be ZrOCl2.8H2O and calcinated to be zirconia. The results showed that zircon sand from Mandor, Landak, West Kalimantan could be synthesized into ZrOCl2.8H2O with NORM 1.2586 ppm and zirconia with NORM = 3.5511 ppm, both products have met the industrial-grade requirement.

Selective Removal of Phosphorus from Seawater Using Mechanochemical Treated Zircon Sand

Selective Removal of Phosphorus from Seawater Using Mechanochemical Treated Zircon Sand

Leaching kinetics of Sodium Zirconate in Hydrochloric Acid based on shrinking core models

The leaching kinetics of sodium zirconate in hydrochloric acid has been studied. Sodium zirconate was the result of melting zircon sand after separation from sodium silicate. The variables studied were temperature, contact time and the mole ratio of solvent to feed (R). These study aims are to determine the optimum conditions, the reaction rate controller and the reaction rate constant (k) and activation energy (Ea) for the leaching process of sodium zirconate (Na2ZrO3).This experiment performed by leaching the sodium zirconate in hydrochloric acid with various temperatures of 50 °C, 70 °C and 90 °C, the mole ratio of solvent to feed of 5, 7 and 9, and various contact time of 10 minutes to 50 minutes. The experimental data were analyzed according to the kinetic models for heterogeneous reaction processes by using shrinking core models. It was found that the leaching of sodium zirconate in hydrochloric acid solution is controlled by chemical reaction with the activation energy was-62.974 kJ/mol. The optimum conditions for the performed experiment in the leaching step were achieved at a temperature of 50 °C, the mol ratio of solvent to feed of 5 and contact time of 50 minutes with the conversion of sodium zirconate was 43.43% and the value of reaction rate constant was 0.0027 min−1.

Mechanical Test of Aluminum-Zirconium-Silicate Composite Prototype with Filler Volume Variation

Recently, ceramic material has become a main object of scientific interest especially in dental material. The advance of dental materials technology has led to use of zirconia-based ceramics for composite filler. In this study, composite filler has been synthesized from natural zircon sand through geopolymerization method. Composite prototype were made with different filler volume to evaluate mechanical properties including hardness number and diametral tensile strength. Samples divided into two groups with 50 wt% filler volume (group A) and 75 wt% filler volume (group B) which 3 samples for each group. The surface micro hardness of each group tested by Leco M-400-H1 vickers microhardness testing machine and for diametral tensile strength tested using universal testing machine (Lloyd) with crosshead speed of 1,0 ± 0,25 mm/min. The data were analyzed using independent sample t-test. The results showed that the average of hardness number on group A was 13,8 VHN while for group B was 24,1 VHN. The average of diametral tensile strength for group A was 20,461 MPa and 27,689 MPa for group B. Statistical result showed that the value (P<0,05). The conclusion, there is a signifficant difference on the result of hardness test between group A (50 wt% filler volume) and group B (75 wt% filler volume) and also on diametral tensile strength test.

Diametral Tensile Strength and Hardness Evaluation of Prototype Composite Based on Natural Zircon Sand Using Geopolymerization Method with Coupling Agent Variation

The widely use of dental composite triggers a lot of research to synthesize composite made from natural sources. One of the natural sources that could be used as a filler of composite is natural zircon sand from Indonesia. The physical properties of dental composite, such as Diametral Tensile Strength (DTS) and hardness could be affected by the filler of the composite. The aim of this research is to determine the value of diametral tensile strength and hardness of prototype composite with natural zircon sand-based filler by using geopolymerization method with various coupling agents. The procedures began from synthesizing Zirconia-Alumina-Silica filler from natural zircon sand using geopolymerization method with two different coupling agents, 3-mercapto propyltrimethoxysilane (3-MPTS) and 3-aminopropyltriethoxysilane (3-APTS), which then mixed with resin matrix to form composite resin, some of the samples were then subjected to a DTS test using Lloyd Universal Testing Machine (5.6 N initial load) until a crack/fracture was formed while some of them was subjected to a hardness test using Vickers Hardness Tester. The results showed the average DTS of dental composite using MPTS coupling agent was 13.78 MPa, while the average DTS of dental composite using APTS coupling agent was 8.90 MPa, and the average hardness result of dental composite coated by 3-MPTS was higher (20.68 VHN) than composite coated by 3-APTS (18.02 VHN). This difference could be affected by filler particle composition, filler surface area and also coupling agent variation. In conclusion, the tensile strength of the prototype resin composite sample group with the natural zircon sand filler using MPTS coupling agent was higher than the APTS coupling agent group.

Radionuclide Transfer in the Zirconium Oxychloride Production Process and the Radiation Effect in a Typical Chinese Enterprise

The radiation impact on the environment from naturally-occurring radioactive materials in zircon sand is an important issue for zirconium product manufacturing enterprises. In this paper, a typical oxychloride production enterprise has been taken as an example to study the radiation effect and environmental pollution during the whole production process. The transfer and enrichment of radionuclides in zircon sand was studied by analyzing their concentrations in samples, such as products and wastes, which were sampled from every studied workshop, so that the dose rate in the environment and typical facility surfaces of each workshop could be measured. The study results show that the transfer and enrichment of radionuclides occur mainly in workshops of acidification, dissolution, concentration and crystallization. Silicon slag adsorbed some radionuclides, but most of the radionuclides in raw materials are transferred and enriched in waste acid by the concentration and crystallization process. Sludge and wastewater still contain a large quantity of radionuclides after treatment by wastewater treatment plants. This results in a significant increase in U-238 and Th-232 concentrations in river water near the main outlet. The average effective dose of all employees in the studied enterprises was 0.94 mSv, and workers from the wastewater treatment plants had the largest annual effective dose at 11 mSv.

Slurry erosive wear and microhardness characteristics with coarse silica sand of dual reinforced particles ADC12 alloy composites

The current research was a comparative study of reinforced ceramic particles and mixing proportion on the microstructural and slurry erosive characteristics for fabricated composites. Dual reinforced particle composites were fabricated by adding combinations of numerous wt% of titanium carbide (TiC) and zircon sand (ZrSiO4) to aluminium die-casting (ADC12) alloy matrix composites. ADC12 alloy composite with titanium carbide and zircon sand samples were also prepared for comparison of dual reinforcement particles on microstructural features and wear behaviour in various slurry concentrations. Titanium carbide (44–60 µm) and zircon sand (20–33 µm) particles are reinforced in the alloy by the two-step stir-casting method. Slurry erosion wear study reveals that the dual particle reinforcement enhances the wear resistance as compared to single-particle reinforcement if mixed in a definite proportion. The study also indicates that a combination of 15% reinforcement of titanium carbide and zircon sand particles in the ratio of 10 and 5 wt% into the composite exhibits better microhardness and wear resistance as compared to other combination.

Decomposition kinetics of zircon sand in NaOH sub-molten salt solution

Abstract Sub-molten salt was applied to the decomposition of zircon sand (ZrSiO4). The kinetics of the decomposition of zircon sand and the effects of reaction temperature, reaction time, NaOH content, agitation speed, and the NaOH/ore mass ratio on the decomposition rate of zircon sand in NaOH sub-molten salt were investigated. The results indicate that the decomposition rate of zircon sand increases with the increase in the reaction temperature, reaction time, and NaOH content. The shrinking-core model with surface chemical reaction-controlled process is the most applicable for the decomposition of zircon sand, with the apparent activation energy of 77.98 kJ/mol. The decomposition product is sodium zirconium silicate (Na2ZrSiO5), and the decomposition rate is higher than 99% under the optimal conditions.

Optimization and Kinetics of Zirconium Oxychloride (ZOC) Dissolution Using HNO<sub>3</sub>

The design of chemical reactor can not be separated from the optimization data and reaction kinetics obtained from the experimental measurement. Through the idea of making the dissolution reactor design, the purpose of this research is to obtain optimization data and dissolution kinetics of Zirconium Oxide Chloride (ZOC) using HNO3. The design of the solvent reactor is required to make the feedstock in the liquid-liquid extraction process continuously. The extraction process is a mini-pilot plant unit as a nuclear-grade zirconia manufacture. The dissolution optimization was carried out by dissolving ZOC solids of zircon sand processed products using HNO3 in a container with some variation of contact time, HNO3 concentration and temperature. While the kinetics data was gained by extracting from the optimization data obtained based on the formula of reaction orders. The investigation result with 6 gr of ZOC and 6M HNO3 concentration obtained the best contact optimum time of 2 minutes and the conversion number (α) of 0.96. The dissolution reaction mechanism was estimated in accordance with the reaction of order 1 with the k value of 1.5879 minutes-1. It was predicted that the reaction mechanism of ZOC dissolution in HNO3 begins with diffuse control and is followed by chemical reaction control. With increasing conversion temperature, the conversion will increase to 0.98, while the reaction also follows the reaction order 1. The optimum temperature at 60 °C, and the correlation between temperature (T) with the calculated reaction rate constant (k) according to the Arrhenius formula yielded an equation of ln k = - 4191,6 / T + 13,903 or k = 13,903.e- 4191,6 / T, with the frequency factor A = 1091430 and the activation energy E = 34,848 kJ / mole.

Particle Size Analysis of the Synthesised ZrO<sub>2</sub> from Natural Zircon Sand with Variation of pH Deposition Using Alkali Fusion-Coprecipitation Method

Zirconia (ZrO2) is one of the refractory ceramic materials that have applications in several fields. The aim of this study was to synthesis ZrO2 from natural zircon sand collected from Kereng Pangi, Central Kalimantan with a variation of pH deposition using alkali fusion co-precipitation method. The synthesized ZrO2 began with the preparation process involved magnetic separation, milling, and leaching with HCl. Furthermore, the alkali fusion process was used KOH solution and heated in an electrical furnace at 700°C for 3 h whereas the co-precipitation process was carried out using a filtrate mixed with the NH4OH solution to reach a pH variation between 3–11 and then precipitated for 12 h. The precipitates were dried in an oven and then calcined at 800°C for 3 h. The structure of synthesized ZrO2 was characterized using XRD and the particle sizes were measured using particle size analyzer (PSA). The XRD analysis showed that the identified phase of zirconia powder is tetragonal with a crystal size in nanometer size. Result of PSA measurement revealed that the crystal size decreased in the range pH of 3 - 7, but increased in the range pH of 7 - 11. The biggest powder particle size could be achieved at 260 nm with pH 7 whereas the smallest size was at 143 nm occurred at pH 3.