Development of post hybrid calcium carbonate for high loaded paper

In papermaking, pre-flocculation of fillers such as ground calcium carbonate (GCC) improves the tensile strength of paper sheets. However, the pre-flocculated fillers mostly suffer from the instability of the floc shape such as the decrease in floc diameter with time elapse after preparation and no improvement of bulk and stiffness. The addition of calcium compounds such as calcium oxide or calcium hydroxide to the pre-flocculated GCC, and injection with carbon dioxide caused pre-flocculated GCC flocs to be covered with newly formed calcium carbonate. This product, called post hybrid calcium carbonate (pHCC), was found to be more stable in size and gave better sheet strength than the pre-flocculated ones. Furthermore, pHCC gave remarkably higher bulk and stiffness than the pre-flocculated flocs did without impairing smoothness that was essential in printing paper. The proper use of pHCC in papermaking could allow the production of high loaded paper with more than 10% higher filler contents, which could reduce paper production cost and save drying energy. The proportion of the newly formed calcium carbonate in pHCC, turbulence intensity at preparation stage, and the effect of storage time were investigated.

Influence of Ground Calcium Carbonate Waste on the Properties of Green Self-Consolidating Concrete Prepared by Low-Quality Bagasse Ash and Rice Husk Ash

Bagasse ash (BA) and rice husk ash (RHA) are by-products from electricity power plants. Ground calcium carbonate waste (GCW) is the by-product of the mining of calcium carbonate (CaCO3) in the color pigment manufacturing industry. Both BA and RHA are classified as low-quality pozzolanic materials, differing from GCW, which contains a high calcium oxide (CaO) content that leads to products equivalent to the hydration reaction. Therefore, GCW is likely able to improve the properties of self-consolidating concrete (SCC) incorporating BA and RHA. This paper discusses the production of green self-consolidating concrete (gSCC) and identifies the benefit of using GCW in gSCC prepared by triple combined GCW (10 and 20 wt%), BA (10, 20, and 30 wt%), and RHA (20 wt%). The results indicate that the majority of the gSCC retain acceptable flowability. The differences in the levels of gSCC substitution and the V-funnel flow results show general correlations with the increase in GCW. The gSCC prepared by 10 wt% GCW associated with 10 wt% BA and 20 wt% RHA was improved significantly. The filling and passing abilities of the gSCC were improved by using GCW. In addition, gSCC achieved mechanical property development and was able to minimize the consumption of OPC by up to 40%.

Elemental Impurities in Pediatric Calcium Carbonate Preparations-High Throughput Quantification and Risk Assessment

Calcium carbonate which is extracted from the Earth in combination with other mineral impurities, is largely used in preparations for pediatric supplements. Elemental impurities in drug products pose toxicological concerns without therapeutic benefits. Thus, it is very urgent to assess the safety of chronic exposure to elements that may be present in trace amounts. In the present study, we developed high throughput ICP-MS method for the quantitative determination of 62 elemental impurities in high matric calcium carbonate samples and validated according to USP 233. Calcium carbonate preparations which state clearly used for child (including neonates, infants, toddlers and children) from 9 manufactures and two types of raw materials (light calcium carbonate and ground calcium carbonate) were investigated in terms of the content and variability of 62 elemental impurities. According to the results, ground calcium carbonate was more suitable to be used in pediatric preparations concerning elemental impurities. Parts of elemental impurities in CaCO3 preparations which are derived from the raw materials and the preparation process, may cause potential risks for children. These results indicate that it is necessary to establish a modern instrumental analysis method to evaluate and control elemental impurities in CaCO3 raw materials and preparations.

Investigation of Composition and Technological Parameters of Highly Porous Gypsum Products Obtaining

A highly porous structure of a gypsum product creation is possible due to the porisation of gypsum mass, using new types of complex gas-forming components. At the same time, it is necessary to determine the technological conditions for the optimal formation of porous gypsum products structure and methods for increasing their strength. The article proposed to use dispersed calcium carbonate and aluminum sulphate, which interaction is the reaction with the release of СО2 for the porisation of the gypsum cast mixture. Micro-reinforcing additives, such as polymeric, basalt and glass fibers were introduced into gypsum composition together with building gypsum and finely ground calcium carbonate to improve the physico-mechanical properties of gas-gypsum. The best results were shown by the gas-gypsum, which included fiberglass. Glass fiber was pre-ground to a specific surface of 190-240 m2 / kg, in order to improve further the physico-mechanical properties of gas-gypsum.

Hybrid Precipitated Calcium Carbonate Containing Wood Flour for Paper Applications – A Comparative Handsheet Study

The main objective of this paper handsheet study is to investigate if a hybrid filler material containing wood flour and precipitated calcium carbonate can replace and/or supplement commercially available ground calcium carbonate and precipitated calcium carbonate mineral filler material for papermaking. The handsheet study contains 25 different furnish mixtures. Four different types of wood flour were used to manufacture the hybrid filler material, including two wood flour blends with a strengthening agent. All handsheet were manufactured with an 80% harwood and 20% softwood mix. The filler content varied between 10, 15 and 20%. The study showed that the hybrid filler material achieved a retention of up to 92.68% as well as a higher caliper of up to 208 μm compared to commercial ground and precipitated calcium carbonate of 120.4 μm and 145.6 μm respectively. Tensile and tear strength did not show an improvement. Elongation and tensile energy absorption did improve of up to 30% with the strength additive containing hybrid filler material. Opacity was improved of up to 10% with the hybrid filler material. Brightness and color values were lower due to the natural brow color of the wood flower material.