Green liquor

The a-D-glucose monohydrate crystals recovered from the crystallizer liquors are washed with cold water in a centrifuge in order to remove residual mother-liquor (greens) from crystal surfaces. The mass of wet crystals, containing 12 to 13% of water (the theoretical value for the monohydrate is 9.1%), is conveyed to a hot-air dryer, where the moisture is lowered to — 8.5%. The crystals are then sieved, in order to afford products of specified granulation, and stored in bins from which railway cars and trucks can be filled. 

Uusitalo [150] analyzed iron sulfides via X-ray analysis to determine their influence on corrosion behavior. Tromans [151] conducted anodic polarization tests and used electron microscopy and including electron diffraction to reveal that sulfide incorporated into the Fe304 film impaired passivation. Honda et al. [152] performed extensive analysis of surface corrosion films in simulated liquor. Clarke and Singbeil [753] completed potentiodynamic polarization scans in white liquor, green liquor, and weak wash liquor at 90°C to investigate the effect of polysulfides on corrosion of carbon and stainless steels. 

Grease Oil Green Copperas Greenland Spar Green Sulfate Liquor Green Vitriol ... 

Chemical recovery ia sodium-based sulfite pulpiag is more complicated, and a large number of processes have been proposed. The most common process iavolves liquor iaciaeration under reduciag conditions to give a smelt, which is dissolved to produce a kraft-type green liquor. Sulfide is stripped from the liquor as H2S after the pH is lowered by CO2. The H2S is oxidized to sulfur ia a separate stream by reaction with SO2, and the sulfur is subsequendy burned to reform SO2. Alternatively, ia a pyrolysis process such as SCA-Bidemd, the H2S gas is burned direcdy to SO2. A rather novel approach is the Sonoco process, ia which alumina is added to the spent liquors which are then burned ia a kiln to form sodium aluminate. In anther method, used particulady ia neutral sulfite semichemical processes, fluidized-bed combustion is employed to give a mixture of sodium carbonate and sodium sulfate, which can be sold to kraft mills as makeup chemical. 

Three major sources in the kraft process are responsible for the majority of the H2S emissions. These involve the gaseous waste streams leaving the recovery furnace, the evaporator and the air stripper, respectively denoted by R), R2 and R3. Stream data for the gaseous wastes are summarized in Table 8.8. Several candidate MSAs are screened. These include three process MSAs and three external MSAs. The process MSAs are the white, the green and the black liquors (referred to as Si, S2 and S3, respectively). The external MSAs include diethanolamine (DBA), S4. activated carbon, Sj, and 30 wt% hot potassium carbonate solution, S6. Stream data for the MSAs is summarized in Table 8.9. Syndiesize a MOC REAMEN that can accomplish the desulfurization task for the three waste streams. 

Two unnamed alkaloids have also been deseribed. One was obtained by Bredemann in work on the alkaloids of white hellebore it occurred in the mother liquors from protoveratrine crystallisation and formed spherical aggregates of needles, m.p. 239-241°. The other was isolated by. Jacobs and Craig during a chromatographic analysis of residual, benzene-soluble alkaloids of green hellebore. It is represented by the formula C27H41 (39)04N, crystallises in six-sided platelets or flat needles, sinters about 130°, effervesces at 170-5°, and on further heating solidifies and finally melts at 272-4° it has [a]n ° — 78° (MeOH). 

This combustion process results in the reduction of inorganics, leading to a molten smelt of sodium carbonate (Na2C03) and sodium sulfide (NajS) on the furnace floor, which is discharged to a tank and dissolved to form green liquor. 

See the NACE Papers Oliver W. Siebert, Correlation of Laboratory Electrochemical Investigations with Field Applications of Anodic Protection, Materials Performance, vol. 20, no. 2, pp. 38-43, February 1981 Anodic Protection, Materials Performance, vol. 28, no. 11, p. 28, November 1989, adapted by NACE from Corrosion Basics— An Introduction. (Houston, Tex. NACE, 1984, pp. 105-107) J. Ian Munro and Winston W. Shim, Anodic Protection— Its Operation and Appheations, vol. 41, no. 5, pp. 22-24, May 2001 and a two-part series, J. Ian Munro, Anodic Protection of White and Green Kraft Liquor Tankage, Part I, Electrochemistry of Kraft Liquors, and Part 11, Anodic Protection Design and System Operation, Materials Performance, vol. 42, no. 2, pp. 22-26, February 2002, and vol. 42, no. 3, pp. 24-28, March 2002. 

Reducing smelting furnaces that produce a high-sulfidity, kraft-like green liquor are now employed at sodium-based sulfite mills. U.S. EPA anticipates that it would be necessary to replace the existing recovery boilers at ammonia-based mills if chemical substitution to a sodium base were employed. Additionally, it is likely that, because the heat value of sodium spent liquor is lower than ammonia spent liquor, evaporator modification may he required if excess capacity does not already exist. 

Green liquor A papermaking process using a mixture of sodium hydroxide and sodium carbonate. 

Analogously, when a colourless aqueous solution of quinolinium chloride (Q+ CP) is mixed with an almost colourless aqueous solution of Na+V(CO)p the well-formed dark green crystals of the vanadate salt precipitate immediately. In each case, the spontaneous separation of the highly coloured salts is made even more dramatic by the absence of colour in the aqueous mother liquors throughout the course of precipitation. The quantitative effects in these coloured salts are observed as broad absorption bands in the spectral region between 350 to beyond 700 nm when they are dissolved in dichloromethane, or in the diffuse reflectance spectra of the crystalline salts. The correspondence of the band maximum (Act) and... 

Molten salt (smelt) tapped from black liquor boilers is quenched and dissolved to form green liquor in tanks near the boiler. On occasion, explosions have resulted which severely damaged the dissolver tank. (These events are different from the smelt-water boiler explosions described later.)... 

Sallack (1955) was the first to publish a study of dissolver-tank explosions. He was motivated by incidents which occurred in a soda pulp operation with a dissolver tank 4.3 m in diameter and 3.7 m tall. Molten smelt entered the tank at the top and was to be broken up with a jet of recirculating green liquor. Agitation of the bulk liquid was also accomplished by air jets. Operation was normally smooth, but if a boiler upset led to a sharp increase in smelt flow, then the smelt-green liquor breakup operation was inefficient and unbroken slugs of smelt could enter the bulk green liquor in the tank. Explosions could then occur. 

To understand the phenomenon better, Sallack carried out a number of laboratory tests wherein he poured about 170 g of smelt into water or green liquor. He also varied the composition and temperature of the smelt. His principal findings were as follows ... 

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