In order to apply the sodium hexametaphosphate method on an industrial basis for preventing scale from adhering to a brine preheater, two on-the-spot tests were continued for a month, respectively, at a salt making factory. From these tests and their supplementary experiments, the following results were obtained:
1. As a result of addition of a minute quantity (15p.p.m.) of sodium hexametaphosphate, there was a considerable decrease in the formation of scale in the brine preheater, and the adherent thus obtained was soft and muddy which could easily be removed. In these tests, the consumption of brine showed an increase of about 5% as compared with normal cases, due to the rise in heat efficiency.
2. It was found that most of the phosphate in the brine moved to bittern and less to common salt and scale during concentration of the brine in the evaporator.

View full abstract

The author made a study on an electrolytic process of producing magnesium bleaching powder (MBP) by using pure lead peroxide anodes manufactured on a commercial basis by the developed electrodeposition method. In this study, the author also investigated effects of anodic current densities of 0.2A/cm² and 0.4A/cm² on the anodic consumption of lead peroxide electrode and the formation of magnesium bleaching powder in the electrolysis of artificial bittern.
The cell was operated batchwise with 30A of electric current applied to 3 liters of electrolyte which was added sodium hydroxide solution at about 30°C. The lead peroxide anode could safely be used in alkaline electrolyte; namely, the anode was absolutely insoluble and was hardly spalled, and thus pure white MBP could be obtained.
Throughout the entire electrolysis batchwise (No.1-No.8), the consumption of anode averaged 103.2mg/1000A·hr (30.9mg/30A·hr), and it amounted to 152.3mg/kg of MBP.
The content of available chlorine of MBP produced by the electrolysis under anodic current density of 0.2A/cm² was about 38.4%, and it averaged 40.5% under the curent density of 0.4A/cm². The electric energy consumed by the MBP containing the above available chlorine was 6.6-7.4kW·hr/kg of MBP, while the consumption of sodium hydroxide was 0.78kg/kg of MBP. The whole current efficiency for the total available chlorine (both in liquid and solid MBP) amounted to 84%-87%.
The magnesium bleaching powder had two kinds of shapes; fine-grain shape and scale-like shape. The fine-grain powder was good in quality possessing 42% of available chlorine, while, as the scale-like precipitate contained about 67% of magnesium hydroxide, its available chlorine declined to approximately 32%.

View full abstract

As mentioned in the previous reports, the magnesium bleaching powder (MBP) obtained through electrolysis of bittern with sodium hydroxide differs in chemical composition from that obtained without sodium hydroxide. Therefore, the author carried out a chemical analysis for the purposes of examining the composition as well as obtaining the chemical formula. Also, the crystalline property of MBP was studied by the powder method of X ray diffraction and the electron-microscopic observation.
The chemical formula of fine-grained MBP was Mg(ClO)OH·Mg(OH)₂, while that of scale-like MBP (produced both in slightly basic and acidic electrolyte) was Mg(ClO)OH·2Mg(OH)₂.
The former indicated a characteristic X ray diffraction pattern in the diffraction chart, indicating 12°30′, 35°24′, 58°33′(2θ). The latter showed nearly the same pattern, but it seemed to be the mixture of Mg(ClO)OH·Mg(OH)₂ and slightly crystalline Mg(OH)₂.
The diffraction of 58°33′(2θ) was so sharp that the MBP crystal was considered to have a structure of regular layer in its direction.

View full abstract

A model plant having 50 pairs of cation and anion exchange membrane of 0.7m² effective area was operated throughout the year for the concentration of sea water. The change in the temperature of raw brine (9-30°) affected the rate of electro-phoretic water transport, and it caused a change in the concentration of produced brine. Power consumption per unit weight of concentrated NaCl was also affected by temperature, but as far as the brine of identical concentration is produced, it does not vary so much because current density should be raised in summer and lowered in winter to keep the concentration steady.

View full abstract

Fundamental experiments were conducted on the softening of hard water with the use of cation exchange membranes. For those experiments was used a cell consisting of three chambers which were partitioned off with two sheets of cation exchange membranes. The sodium chloride solution or sea water was recycled in the chambers on the both sides of the cell, and calcium chloride solution or tap water was filled in the central chamber. After the ion exchange transfer, the concentration of both calcium and chloride ions in the central chamber was measured with the following results:
The decreasing rate of the calcium ion in the central chamber showed an increase in accordance with the increase in its concentration, but it was not influenced by the concentration of the sodium ions in the both side chambers. No influence was exerted on the rate by the coexistence of a small amount of calcium ion in the solution of sodium chloride.
The above experiments revealed that sea water could be employed in the softening of water.

View full abstract