Chemicals used for treatment of water intended for human consumption. Calcium carbonate, high-calcium lime, half-burnt dolomite, magnesium oxide, calcium magnesium carbonate and dolomitic lime. Test methods

BackgroundDespite adverse effects such as constipation, vascular calcification, and hypercalcemia, calcium-based salts are relatively affordable and effective phosphate binders that remain in widespread use in the dialysis population. We conducted a pilot study examining whether the use of a combined magnesium/calcium-based binder was as effective as calcium carbonate at lowering serum phosphate levels in peritoneal dialysis (PD) patients.MethodsThis was a cross-over, investigator-masked pilot study in which prevalent PD patients received calcium carbonate alone (200 mg calcium per tablet) or calcium magnesium carbonate (100 mg calcium, 85 mg magnesium per tablet). Primary outcome was serum phosphate level at 3 months. Analysis was as per protocol.ResultsTwenty patients were recruited, 17 completed the study. Mean starting dose was 11.35 ± 7.04 pills per day of MgCaCO3and 9.00 ± 4.97 pills per day of CaCO3. Mean phosphate levels fell from 2.13 mmol/L to 2.01 mmol/L (95% confidence interval (CI): 1.76 – 2.30, p = 0.361) in the MgCaCO3group, and 1.81 mmol/L (95% CI: 1.56 – 2.0, p = 0.026) in the CaCO3alone group. Six (35%) patients taking MgCaCO3and 9 (54%) taking CaCO3alone achieved Kidney Disease Outcomes Quality Initiative (KDOQI) serum phosphate targets at 3 months. Diarrhea developed in 9 patients taking MgCaCO3and 3 taking CaCO3. Serum magnesium exceeded 1.4 mmol/L in 5 patients taking MgCaCO3while serum calcium exceeded 2.65 mmol/L in 3 patients receiving CaCO3. When compared to the initial dose, the prescribed dose at 3 months was reduced by 44% (to 6.41 tablets/day) in the MgCaCO3group and by 8% (to 8.24 pills per day) in the CaCO3alone group.ConclusionCompared with CaCO3alone, the preparation and dose of MgCaCO3used in this pilot study was no better at lowering serum phosphate levels in PD patients, and was associated with more dose-limiting side effects.

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Decarbonising the Portland and other Cements—Via Simultaneous Feedstock Recycling and Carbon Conversions Sans External Catalysts

Polymers ◽

10.3390/polym13152462 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2462

Author(s):

Sheila Devasahayam

Keyword(s):

Carbon Dioxide ◽

Calcium Carbonate ◽

Magnesium Oxide ◽

Carbon Footprint ◽

Elevated Temperatures ◽

Clean Energy ◽

Magnesium Carbonate ◽

Methane Emissions ◽

Carbon Conversion ◽

Waste Plastics

The current overarching global environmental crisis relates to high carbon footprint in cement production, waste plastic accumulation, and growing future energy demands. A simultaneous solution to the above crises was examined in this work. The present study focused on decarbonizing the calcination process of the cement making using waste plastics and biowastes as the reactants or the feedstock, to reduce the carbon footprint and to simultaneously convert it into clean energy, which were never reported before. Other studies reported the use of waste plastics and biowastes as fuel in cement kilns, applicable to the entire cement making process. Calcination of calcium carbonate and magnesium carbonate is the most emission intensive process in cement making in Portland cements and Novacem-like cements. In the Novacem process, which is based on magnesium oxide and magnesium carbonates systems, the carbon dioxide generated is recycled to carbonate magnesium silicates at elevated temperatures and pressures. The present study examined the Novacem-like cement system but in the presence of waste plastics and biomass during the calcination. The carbon dioxide and the methane produced during calcination were converted into syngas or hydrogen in Novacem-like cements. It was established that carbon dioxide and methane emissions were reduced by approximately 99% when plastics and biowastes were added as additives or feedstock during the calcination, which were converted into syngas and/or hydrogen. The reaction intermediates of calcination reactions (calcium carbonate–calcium oxide or magnesium carbonate–magnesium oxide systems) can facilitate the endothermic carbon conversion reactions to syngas or hydrogen acting as non-soot forming catalysts. The conventional catalysts used in carbon conversion reactions are expensive and susceptible to carbon fouling. Two criteria were established in this study: first, to reduce the carbon dioxide/methane emissions during calcination; second, to simultaneously convert the carbon dioxide and methane to hydrogen. Reduction and conversion of carbon dioxide and methane emissions were facilitated by co-gasification of plastics and bio-wastes.

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The dissociation of dolomite

Mineralogical Magazine and Journal of the Mineralogical Society ◽

10.1180/minmag.1923.020.101.03 ◽

1923 ◽

Vol 20 (101) ◽

pp. 54-59 ◽

Cited By ~ 1

Author(s):

Cecil S. Garnett

Keyword(s):

Carbon Dioxide ◽

Calcium Carbonate ◽

Magnesium Oxide ◽

Magnesium Carbonate ◽

Considerable Reduction ◽

Refractory Minerals

That dolomite (CaCO3 . MgCO3) on being heated behaves as though it were a mixture of the two carbonates by dissociating in two distinct stages, appears to be the widely accepted opinion. Thus it is staled (Mem. Geol. Survey, Special Reports on Min. Resources, London, 1920, vol. 16, ‘Refractory Minerals’, p. 102) ‘On calcination, dolomite undergoes a progressive dissociation which may be considered chemically as covering two distinct stages. The first effect of rising temperature is the expulsion of carbon dioxide from the magnesium carbonate contained in the dolomite and the formation of a mixture of magnesium oxide and calcium carbonate, accompanied by a considerable reduction in volume… . Complete calcination results in the expulsion of the remaining carbon dioxide, a still further reduction in volume, and the production of a dense crystalline aggregate of magnesium and calcium oxides.’

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Chemicals used for treatment of water intended for human consumption. Calcium magnesium carbonate

10.3403/30207848 ◽

2011 ◽

Keyword(s):

Magnesium Carbonate ◽

Human Consumption ◽

Calcium Magnesium

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Chemicals used for treatment of water intended for human consumption. Calcium magnesium carbonate

10.3403/30207848u ◽

2015 ◽

Keyword(s):

Magnesium Carbonate ◽

Human Consumption ◽

Calcium Magnesium

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A method for measuring the in-plane compressive strength and the compression behavior of coating layers

TAPPI Journal ◽

10.32964/tj10.7.29 ◽

2011 ◽

Vol 10 (7) ◽

pp. 29-34

Author(s):

TEEMU PUHAKKA ◽

ISKO KAJANTO ◽

NINA PYKÄLÄINEN

Keyword(s):

Tensile Strength ◽

Compressive Strength ◽

Calcium Carbonate ◽

Coating Layer ◽

Test Methods ◽

Coating Films ◽

Precipitated Calcium Carbonate ◽

Coating Color ◽

Mineral Coatings ◽

Styrene Butadiene

Cracking at the fold is a quality defect sometimes observed in coated paper and board. Although tensile and compressive stresses occur during folding, test methods to measure the compressive strength of a coating have not been available. Our objective was to develop a method to measure the compressive strength of a coating layer and to investigate how different mineral coatings behave under compression. We used the short-span compressive strength test (SCT) to measure the in-plane compressive strength of a free coating layer. Unsupported free coating films were prepared for the measurements. Results indicate that the SCT method was suitable for measuring the in-plane compressive strength of a coating layer. Coating color formulations containing different kaolin and calcium carbonate minerals were used to study the effect of pigment particles’ shape on the compressive and tensile strengths of coatings. Latices having two different glass transition temperatures were used. Results showed that pigment particle shape influenced the strength of a coating layer. Platy clay gave better strength than spherical or needle-shaped carbonate pigments. Compressive and tensile strength decreased as a function of the amount of calcium carbonate in the coating color, particularly with precipitated calcium carbonate. We also assessed the influence of styrene-butadiene binder on the compressive strength of the coating layer, which increased with the binder level. The compressive strength of the coating layer was about three times the tensile strength.

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