Production of sodium

Castner-Kellner cell An electrolytic cell for the production of sodium hydroxide. ... 

By the electrolysis of concentrated sodium chloride solution this process was initially used primarily for the production of sodium hydroxide but the demand for chlorine is now so great that the chlorine is a primary and not a by-product. 

Potassium Nitrate. Potassium nitrate, known but Httle used as a fertilizer for many years, may be reclaimed as a by-product of the production of sodium nitrate from natural deposits of caflche in Chile. KNO also has been produced by the double decomposition reaction between sodium nitrate and potassium chloride ... 

The reaction of formate salts with mineral acids such as sulfuric acid is the oldest iadustrial process for the production of formic acid, and it stiU has importance ia the 1990s. Sodium formate [141-53-7] and calcium formate [544-17-2] are available iadustriaHy from the production of pentaerythritol and other polyhydric alcohols and of disodium dithionite (23). The acidolysis is technically straightforward, but the unavoidable production of sodium sulfate is a clear disadvantage of this route. 

An expandable anode involves compression of the anode stmcture using cHps during cell assembly so as not to damage the diaphragm already deposited on the cathode (Eig. 3a). When the cathode is in position on the anode base, 3-mm diameter spacers are placed over the cathode and the cHps removed from the anode. The spring-actuated anode surfaces then move outward to bear on the spacers, creating a controlled 3-mm gap between anode and cathode (Eig. 3b). This design has also been appHed to cells for the production of sodium chlorate (22). 

In the production of sodium 3-hydroxy-2,7-naphthaIenedisulfonate/7Jj5 -j5 -J7 (R-salt) (38), 2-naphthol is stirred with excess 98 wt % sulfuric acid at 60°C, sodium sulfate is added, and the mixture is stirred and heated for 36 h at 105—122°C (77). The charge is diluted with water and salted out with ca 15 wt % sodium chloride at 60°C to give R-salt in 68% yield. 

Perchlorates. Historically, perchlorates have been produced by a three-step process (/) electrochemical production of sodium chlorate (2) electrochemical oxidation of sodium chlorate to sodium perchlorate and (4) metathesis of sodium perchlorate to other metal perchlorates. The advent of commercially produced pure perchloric acid directly from hypochlorous acid means that several metal perchlorates can be prepared by the reaction of perchloric acid and a corresponding metal oxide, hydroxide, or carbonate. 

Chemical precipitation and solvent extraction are the main methods of purifying wet-process acid, although other techniques such as crystallisa tion (8) and ion exchange (qv) have also been used. In the production of sodium phosphates, almost all wet-process acid impurities can be induced to precipitate as the acid is neutralized with sodium carbonate or sodium hydroxide. The main exception, sulfate, can be precipitated as calcium or barium sulfate. Most fluorine and siUca can be removed with the sulfate filter cake as sodium fluorosiUcate, Na2SiFg, by the addition of sodium ion and control of the Si/F ratio in the process. 

Alkali Meta.IPhospha.tes, A significant proportion of the phosphoric acid consumed in the manufacture of industrial, food, and pharmaceutical phosphates in the United States is used for the production of sodium salts. Alkali metal orthophosphates generally exhibit congment solubility and are therefore usually manufactured by either crystallisation from solution or drying of the entire reaction mass. Alkaline-earth and other phosphate salts of polyvalent cations typically exhibit incongment solubility and are prepared either by precipitation from solution having a metal oxide/P20 ratio considerably lower than that of the product, or by drying a solution or slurry with the proper metal oxide/P20 ratio. 

Commercial grades of sodium aluminate are obtained by digestion of aluminum tnhydroxide in aqueous caustic at atmospheric pressure and near the boiling temperature (7). Digestion of the aluminum hydroxy oxide in aqueous sodium hycboxide [1310-73-2] requbes pressures of up to 1.38 MPa (13.6 atm) and temperatures of about 200°C. Dry sodium aluminate is obtained by evaporation of water. Several processes for the production of sodium aluminate are known that do not reqube the addition of water. In one process, bauxite reacts with molten sodium hycboxide at approximately 400°C (8) in... 

Electrolysis of Fused Sodium Hydroxide. The first successful electrolytic production of sodium was achieved with the Castner cell (2) ... 

Historically, U.S. production of sodium was 70—85% of world production. As lead compounds were phased out of gasoline in North America, this situation changed (Table 8). 

The armual world production of sodium nitrate was steady throughout the early 1990s. About 85% is suppHed by the natural product. The maximum world production of sodium nitrate occurred around 1930, at 3,000,000 t/yr, but the highest production levels attained by the Chilean nitrate industry (ca 2,900,000 t/yr) occurred in the late 1920s. Synthetic sodium nitrate production peaked in the mid-1930s at 730,000 t/yr. During that period, the Chilean industry production decreased to 1,360,000 t/yr. 

As of 1996 world production of sodium nitrate was about 520,000 metric tons annually. Of this quantity, some 450,000 t (86%) are produced in Chile from natural deposits by SQM Nitratos and distributed worldwide by several affOiates, eg, Chilean Nitrate Corporation in the United States and Nitrate Sales International in Belgium. The remainder, ca 70,000 t, is manufactured mainly in Europe, Japan, and Russia, generally as a by-product of nitric acid production. Additionally, China is known to manufacture some unknown but significant volumes of sodium nitrate for domestic use. 

Industrial production of sodium nitrite is by absorption of nitrogen oxides (NO ) into aqueous sodium carbonate or sodium hydroxide. NO gases originate from catalytic air oxidation of anhydrous ammonia, a practice common to nitric acid plants ... 

Economic Aspects and Uses. Production and pricing information for Na2S through 1991 are Hsted in Table 2. U.S. production of sodium sulfide increased rapidly from 1965 through 1972 and then began to decrease. The last year that the U.S. Bureau of the Census released official production figures was in 1974 because at that time there were only three producers of sodium sulfide. Estimates indicate that 1991 production fell to the levels of the late 1950s. List prices have increased since 1974 as sulfur and sodium hydroxide prices have increased. 

Literature reports iadicate that sodium sorbate causes weak genotoxic effects such as chromosomal aberrations and mutations ia mammalian cells (172,173). This effect is thought to be caused by oxidative products of sodium sorbate ia stored solutions (173—175). The main oxidation product of sodium sorbate, 4,5-oxohexenoate, is mutagenic ia a Salmonella mammahan-microsome test (176). Sorbic acid and potassium sorbate were not genotoxic under the same test procedures (167,172,174—177). 

Uses. The dominant use of sulfur dioxide is as a captive intermediate for production of sulfuric acid. There is also substantial captive production in the pulp and paper industry for sulfite pulping, and it is used as an intermediate for on-site production of bleaches, eg, chlorine dioxide or sodium hydrosulfite (see Bleaching agents). There is a substantial merchant market for sulfur dioxide in the paper and pulp industry. Sulfur dioxide is used for the production of chlorine dioxide at the paper (qv) mill site by reduction of sodium chlorate in sulfuric acid solution and also for production of sodium dithionite by the reaction of sodium borohydride with sulfur dioxide (315). This last appHcation was growing rapidly in North America as of the late 1990s. 

Miscellaneous. In ore flotation, sodium sulfite functions as a selective depressant. In textile processing, sodium sulfite is used as a bleach for wood (qv) and polyamide fibers and as an antichlor after the use of chlorine bleach. Synthetic appHcations of sodium sulfite include production of sodium thiosulfite by addition of sulfur and the introduction of sulfonate groups into dyestuffs and other organic products. Sodium sulfite is useful as a scavenger for formaldehyde in aminoplast—wood compositions, and as a buffer in chrome tanning of leather. 

Economic Aspects. U.S. production of sodium metabisulfite is estimated to be well ia excess of 45,000 t, but statistics are confused by some commingling with sodium sulfite. The principal U.S. producers are Rhc ne-Poulenc and General Chemical. The price ia mid-1995 was 0.63/kg for anhydrous sodium bisulfite. 

Sodium dithionite solution can be produced on-site utilizing a mixed sodium borohydride—sodium hydroxide solution to reduce sodium bisulfite. This process has developed, in part, because of the availabiHty of low cost sulfur dioxide or bisulfite at some paper mills. Improved yields, above 90% dithionite based on borohydride, can be obtained by the use of a specific mixing sequence and an optimized pH profile (360,361). Electrochemical technology is also being offered for on-site production of sodium hydrosulfite solution (362). 

After World War I, other chlohne-based bleaches were developed. In 1921 the use of chlorine dioxide for bleaching fibers was reported followed by the development of the commercial process for large-scale production of sodium chlorite. In 1928 the first dry calcium hypochlorite containing 70% available chlorine was produced in the United States. This material largely replaced bleaching powder as a commercial bleaching agent. 

The source of Argentine production is an open-pit tincal mine at 4000 m above sea level. A modem plant is located near the mine site. Total production of sodium borates is approximately 200,000 metric tons per year (101). 

Whereas there is no commercial production of sodium pentaborate pentahydrate, the compound can be prepared by crystallizing a borax-boric acid solution having a Na20 B202 mol ratio of 0.2. 

Production of Sodium Borohydride. In the pulp and paper industry, sodium borohydride is used to generate sodium hydrosulfite (sodium dithionite), a bleaching agent, from sodium bisulfite. Methyl borate is used as an intermediate in the production of sodium borohydride (33). 

Calcium cyanamide can be converted to calcium cyanide [592-01-8], used ia cyanidation of metallic ores and production of sodium cyanide and ferrocyanides (11) (see Cyanides). Calcium cyanamide has also been used to make cyanamide which ia turn is the starting material for important iadustrial organic syntheses. 

Significant quantities of calcium chloride are produced in the United States, Canada, Mexico, Germany, Belgium, Sweden, Finland, Norway, and Japan. Historically calcium chloride was a by-product of sodium carbonate (soda ash) production. The sole U.S. producer via this route closed operation in the 1980s and consoHdated production in Canada. 

The specific use appHcations of sodium chlorite varies from country to country. Important factors are the regulatory and environmental laws in effect for air and water quaUty standards. Sodium chlorite is generally priced at about four to six times the cost of sodium chlorate. The Hst price of 80% technical-grade NaC102 in January 1991 was 2.65/kg (146). In 1990, the estimated consumption of sodium chlorate for the production of sodium chlorite in Canada was about 2700 metric tons and about 9100 metric tons in the United States (74). In Western Europe, the 1990 chlorate consumption estimate was about 11,000 metric tons. A summary of 1991 U.S. and foreign sodium chlorite producer annual plant capacities in various world market areas is given in Table 3. 

Fig. 2. Flow diagram for the production of sodium chromate, sodium dichromate, and chromic acid flake and crystals.

The prices of some important chromium chemicals are given ia Table 4, and production and shipment data for sodium chromate and dichromate are given ia Table 5. Data for the productioa and shipment of chromic acid have not been available siace 1972. However, traditionally CrO has held at about 30—35% of sodium dichromate production. The estimated capacity for domestic production of sodium dichromate is 150,000 to 200,000 t/yr. 

Plants for the production of sodium cyanide from Andmssow process or from acrylonitrile synthesis by-product hydrogen cyanide are operating in the United States, Italy, Japan, the UK, and AustraUa. In Germany, sodium cyanide is produced from BMA hydrogen cyanide, and in AustraUa one plant uses Fluohmic process hydrogen cyanide. 

A 50-galIon stirred pot reactor was used for the production of sodium aluminum hydride, which reacts exothermally with water with enough heat to cause the hydrogen that is released to explode. 

In boiling ethanol, under nitrogen and in the presence of palladized charcoal, 2-acetyl-l,4-dihydro-3-methylquinoxaline (30) undergoes dismutation to give a mixture of 2-acetyl-3-methylquinoxaline, 2-acetyl-l,2,3,4-tetrahydro-3-methylquinoxaline (33), and 2-l -hydroxy-ethyl-3-methylquinoxaline (34), The latter compound is the product of sodium borohydride or Meerwein-Ponndorf reduction of 2-acetyl-3-methylquinoxaline. 

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