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By-product Gypsum
Published in Manjit Singh, Gypsum & Gypsum Products, 2023
On calcining phosphogypsum at 750°C to anlydrite, the impurities of dicalcium phosphate (CaHPO4.2H2O) gets converted into calcium pyrophosphate (Ca2P2O3). It is insoluble in water and thus harmless. Data obtained before and after calcination showed no loss of P2O5 on heating but reduction in fluoride content through volatilization.
Flotation separation of limonite from calcite with sodium oleate: effects of calcite dissolution and addition of sodium pyrophosphate
Published in Mineral Processing and Extractive Metallurgy, 2019
Yuhua Wang, Dongfang Lu, Liguang Wang
SPP was found effective in depressing the flotation of limonite, and the effect of SPP dosage on the flotation of limonite is shown in Figure 7. Also shown is the flotation of calcite for comparison. At pH 9.5 and 3.0 × 10−4 mol/L sodium oleate, as the dosage of SPP was increased to over 1.0 × 10−4 mol/L, limonite was fully depressed (limonite recovery is less than 3%). In contrast, the flotation recovery of calcite remained over 92% and was indifferent to the addition of SPP. Therefore, SPP shows its potential as a depressant for limonite flotation using sodium oleate as a collector. One possible explanation is that SPP might react with active sites of Ca on calcite and Fe on limonite; the complex of calcium pyrophosphate is easy to separate from calcite due to the dissolving of calcite, but iron pyrophosphate absorbed firmly on the surface of limonite and hampered the adsorption of sodium oleate. Rashchi and Finch (2000) had also pointed out the possible blocking mechanism of phosphate ions for oleate adsorption. In addition, chain phosphates are more capable of holding calcium than iron in solution. Li and Lu (1983) stated that the phosphate did not precipitate the calcium ion in the pulp but dissolved the calcium ion on the mineral surface.
Novel carbonized bone meal for defluoridation of groundwater: Batch and column study
Published in Journal of Environmental Science and Health, Part A, 2018
Somak Chatterjee, Sanjay Jha, Sirshendu De
FTIR analysis of the optimized CBM (sample G) is presented in Figure 3(b). The adsorption peaks are found above 3,000 cm−1, indicating the aromatic nature of the compound. The bands stretching between the peaks 3,813 and 3,391 (cm−1) correspond to the hydroxy group (H-bonded OH stretch).[33] There are clusters of peaks noted in between 2,341 and 1,846 cm−1. This corresponds to the medial alkyne (CC) and methoxy related compounds (CH3-O).[33] It should be noted here that the stretch corresponding to the 1,463–1,793 cm−1 represents purines, which is common within the organic matrix of the bone meal. Presence of phosphate groups (both organic and aliphatic) is characterized by the peaks at 1,335 and 1,062 cm−1. Presence of carbonyl compounds is depicted by the peaks occurring in the lower range of the spectra (872–712 cm−1). Peaks at 559 and 464 cm−1 indicate presence of α-form of calcium pyrophosphate. Suppression of the peaks at consecutive wavelengths, after immersion in fluoride solution, suggests that adsorption of fluoride within CBM.
Device solutions for a challenging spine surgery: minimally invasive transforaminal lumbar interbody fusion (MIS TLIF)
Published in Expert Review of Medical Devices, 2019
Arash J. Sayari, Dil V. Patel, Joon S. Yoo, Kern Singh
Ceramics are inorganic compounds of hydroxyapatite or tricalcium phosphate and only offer osteoconductive properties. Therefore, they function primarily as bone graft extenders. Ceramics have inferior mechanical strength and are susceptible to resorption. Studies have demonstrated poorer fusion rates after MIS TLIFs when ceramics are used alone [56]. However, when combined with local autograft, these compounds create an advantageous lattice for improved bone growth. Other ceramics including calcium phosphate, calcium sulphate, and calcium pyrophosphate are also commonly used in MIS TLIF, but their efficacy remains to be fully delineated. Given the significant increase in cost of using ceramics, currently, their indications are limited to case-by-case bases with scares local bone.