A rapid and reliable performance test will enable fast and suitable selection of binder for each service environment. In order to evaluate the possibility of using smaller specimens to accelerate the sulphate resistance tests, Portland cement mortar specimens of sizes 20 × 20 × 160 mm, 25 × 25 × 280 mm and 40 × 40 × 160 mm were continuously immersed in 50 g/l sodium sulphate solution and various physical and microstructural characteristics were evaluated at different ages. Additionally, the depth of deterioration and the alteration in binder chemistry was investigated using microCT scan and SEM-BSE along with EDX analysis. The XRD pattern confirms that expansion of specimen is related to the fraction in the cross section altered by the formation of ettringite and gypsum. The expansion and evolution of flexural strength showed a close correlation, notwithstanding a concurrence between the depth of deterioration and evolution of dynamic modulus. This paper discusses the relevance or possibility of using various test methods and their consistency in sulphate attack measurements. The investigation shows that smaller specimens can be considered as a means to accelerate the typical immersion test method for sulphate attack.

The effect of specimen size on deterioration due to external sodium sulphate attack in full immersion studies

In Chap. 11 we focused on potash deposits and concluded that the larger accumulations of potash that dominate the rock record are marine-derived. That is, the larger potash deposits that are conventionally mined across the world accumulated in ancient tectonic (megahalite) basins with no Quaternary counterpart. We shall now discuss various accumulations of other evaporite salts and related products that are exploited as economic resources, namely the borates, Na-carbonates, Na-sulphates, lithium salts and zeolites, along with short considerations of exploited gypsum and halite deposits (Table 12.1). Other than gypsum and halite, they are typically lacustrine precipitates or brine products, formed by the evaporation of waters with nonmarine ionic proportions and in supra-sealevel depositional settings that do have same-scale pre-Quaternary counterparts (Warren 2010). The marine-derived megahalite and megasulphate deposits, which have no same-scale modern counterparts, were the focus of much of the discussion in earlier chapters. Aspects of these halite and gypsum deposits are only mentioned in passing in this chapter, via a discussion of their annual production volumes and uses, but they are the highest ranked deposits in terms of the weight utilized as mineable or extractable natural resources (Table 12.2). Next in terms of extracted volume is soda ash, then the potash salts, then with an order of magnitude less is salt cake and the borate salts.

Non-Potash Salts: Borates, Na-Sulphates, Na-Carbonate, Lithium Salts, Gypsum, Halite and Zolites

The Panel on Food Additives and Flavourings (FAF) provided a scientific opinion re-evaluating the safety of sulphuric acid (E 513) and its sodium (E 514), potassium (E 515), calcium (E 516) and ammonium (E 517) salts when used as a food additive. The Panel considered that adequate exposure and toxicity data were available. Sulphuric acid and its sodium, potassium, calcium and ammonium salts (E 513, E 514, E 515, E 516, E 517) are authorised food additives in the EU, in accordance with Annex II and Annex III to Regulation (EC) No 1333/2008. In the refined estimated exposure non brand-loyal scenario, mean exposure ranged from 0.4 mg sulphate/kg body weight (bw) per day in infants to 35 mg sulphate/kg bw per day in toddlers. The high percentile of exposure ranged from 3 mg sulphate/kg bw per day in adolescents to 68 mg sulphate/kg bw per day in toddlers. The Panel considered sulphates of low acute toxicity and there is no concern with respect to genotoxicity and carcinogenicity. The Panel noted that the exposure to sulphates at mean and 95th percentile in the non brand-loyal scenario as well as in the other scenarios, is far below the 300 mg/kg a dose that induced laxative effect in humans. Based on the toxicological database available, the Panel concluded that the exposure to sulphuric acid (E 513), sodium sulphate (E 514), potassium sulphates (E 515), calcium sulphate (E 516) and ammonium sulphate (E 517) does not raise a safety concern at the reported uses and use levels and there is no need for a numerical acceptable daily intake (ADI).

https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/j.efsa.2019.5868

Re‐evaluation of sulphuric acid and its sodium, potassium, calcium and ammonium salts (E 513, 514 (i), 514 (ii), 515 (i), 515 (ii), 516 and 517) as food additive

Sodium sulfate, Na2SO4, is principally used as a filler in soaps and detergents and in the manufacturing process of kraft paper. These uses consume about 80% of the world’s production. It is also used in glassmaking, in textiles, glass, and carpet fresheners. Both sodium sulfate and sodium bisulfate, NaHSO4, are used to adjust the pH of various solutions and to dilute certain dyes. Sodium bisulfate is a mild acid safe for household cleaning and where a mild acid is needed. About half of the sodium sulfate production is derived from naturally occurring salts and brines. The other half is produced as a by-product in the manufacture of rayon, sodium dichromate, resorcinol, and silica pigments.



Sodium hydrosulfide, sodium sulfide, and sodium tetrasulfide are somewhat interchangeable in many applications. Uses range from ore flotation to leather tanning and from pulp processing in kraft pulping to lubricant manufacture. The processes used to manufacture these compounds are described. Sulfide solubilities are discussed.


Keywords:

sodium sulfate;
soap;
rayon;
sodium sulfite;
sodium sulfate;
sodium sulfate decahydrate;
sodium bisulfate;
minerals;
glauber’s salt;
paper;
detergents;
sodium hydrosulfide;
sodium sulfide;
sodium tetrasulfide;
pulp processing;
ore flotation

David R. Bush

Papers

Sodium Sulfates and Sulfides