Soda Liquor Research Articles

Combustion properties of reduced-lignin black liquors

The growing interest in production of green chemicals and biofuels from biomass provides an incentive for pulp mills to identify new possibilities in recovering more wood components from the pulping process. One possibility is to use lignin, separated from black liquor. We undertook this work to determine the combustion properties of reduced-lignin black liquors—two kraft liquors and one soda liquor—in a laboratory-scale, singleparticle furnace. The combustion times, maximum swollen volume, nitric oxide formation, cyanate formation, and sulfur release were measured for the original liquors, the filtrates, and intermediate levels of lignin reduction. Combustion experiments were conducted at 900°C in 10% oxygen. Cyanate formation experiments were carried out by pyrolyzing the droplets at 800°C in 100% nitrogen to form a char. The chars were then gasified at 800°C in a 13% carbon dioxide/87% nitrogen atmosphere to obtain the smelt. Sulfur release was studied by pyrolyzing the samples at temperatures ranging from 300°C to 900°C. Liquors with the lowest lignin content had a smaller maximum swollen volume than the original sample. The devolatilization time was not affected by the lignin removal to any great extent, but lignin removal did have a clear effect on the char burning time. The amount of formed nitric oxide (g N/kg black liquor solids) remained constant or decreased slightly with increasing lignin removal in the kraft liquor samples, while for the soda samples the amount of nitric oxide formed increased. The amount of cyanate decreased clearly when comparing the samples with lowest lignin content to the original liquor samples. The peak sulfur release occurred at 500°C for both kraft liquors. In almost all experiments, the share of sulfur released was highest for the original samples and lowest for the sample with lowest lignin content. These results provide new data on combustion properties for reduced-lignin black liquors and indicate that for lignin removal levels up to about 20%, no significant changes are expected in the combustion behavior.

Thermal transformation of pyrophyllite and alkali dissolution behavior of silicon

Thermochemical behavior of pyrophyllite was characterized by using XRD, FTIR, TG-DTA and MAS NMR techniques. Pyrophyllite experiences a series of solid-state phase transformations during thermal treatment. Dehydroxylation of pyrophyllite is completed at 880°C, and the original layered framework is inherited in dehydroxylated pyrophyllite. Up to 1100°C, the layered framework is collapsed thoroughly, with formation of amorphous SiO2 and mullite. Above 1200°C, cristobalite crystallizes from amorphous SiO2, and mullitization is promoted dramatically. The alkali leaching results show that amorphous SiO2 in the thermally activated pyrophyllite is soluble in caustic soda liquor, while mullite is not, and the formation of sodium aluminosilicate hydrate of 0.95Na2O·Al2O3·3.25SiO2·4.79H2O during alkali leaching diminishes the dissolution ratio of silica. The alkali dissolution behavior of silicon demonstrates an innovative process for removing silica from pyrophyllite by using thermochemical activation (TCA) followed by alkali leaching, which can be applied to desilication of bauxite ore and preparation of alumina-base porous material. A desilication of 84% was obtained from the tested ore containing 90% pyrophyllite at the optimal thermochemical activation conditions of temperature 1100–1150°C and time 90–20min. The good alkali dissolution characteristic of silica also is a cogent evidence on the formation of amorphous silica during the thermal treatment of pyrophyllite.

Studies on the effect of prehydrolysis and amine in cooking liquor on producing dissolving pulp from jute (Corchorus capsularis)

Dissolving pulps are the raw materials for the production of many different end-products. Jute is a very good source of cellulose. In this investigation, jute fiber was subjected to pulping in soda process in order to produce dissolving pulp under different prehydrolysis conditions and compared with prehydrolysed kraft pulp from jute. An increase of the prehydrolysis temperature or H2SO4 in prehydrolysis liquor increased the α-cellulose content and decreased the viscosity of pulp. The effect of ethylenediamine in soda liquor was also investigated when producing dissolving pulp. Jute fiber produced pulp having 90–97% α-cellulose. Ethylenediamine in soda liquor produced pulp of higher yield, viscosity and higher α-cellulose content than that of prehydrolysis soda or kraft pulp. The α-cellulose content and viscosity were increased with the increase of amine in soda liquor. The kappa number of dissolving pulp from jute was very low (9–5), which indicated that less bleaching chemicals are required for bleaching. The bleachability of soda-ethylenediamine pulp was lower than prehydrolysed soda and kraft pulp in ECF bleaching sequences. The bleachability of soda-ethylenediamine pulp was improved at the sacrifice of pulp yield when prehydrolysis was done prior to pulping. The alkali solubility S10 and S18 were 4–9 and 2–4%, respectively.

Process for the production of dissolving pulp from Trema orientalis (nalita) by prehydrolysis kraft and soda-ethylenediamine (EDA) process

This paper presents a preliminary study for the production of dissolving pulp from Trema orientalis (Nalita). Water prehydrolysis kraft and soda-ethylenediamine (EDA) pulping for the production of dissolving pulp from T. orientalis was investigated. Prehydrolysis at 150 and 170 oC did not produce pulp with high α-cellulose content when using the kraft process. But addition of 0.25 % H2SO4 in prehydrolysis liquor increased the purity of the pulp with the sacrifice of pulp yield and viscosity. The soda-EDA process produced better pulp yield, kappa number, viscosity, and α-cellulose content as compared to the kraft process. Increasing EDA charge in the soda liquor increased pulping selectivity and α-cellulose content. Degraded cellulose (R18-R10) in soda-EDA pulp was lower than kraft pulp. But the bleachability of soda-EDA pulp was inferior as compared to kraft pulp in DED bleaching.

Thermal activation and alkali dissolution of silicon from illite

TGA, DTA, FTIR, XRD and 29Si MAS NMR were used to investigate the thermal activation of illite. Illite experiences a series of thermal solid-state phase transformations. Dehydroxylation at 400∼700 °C forms dehydrated illite, which remains the layered framework of illite. From 700 °C to 1093 °C, Si–O tetrahedral framework remains unchanged. When heated above 1093 °C, the layered structure is destroyed and an amorphous silica-rich glass phase is formed. The mullitization occurs when the temperature exceeds 1100 °C. XRD and FTIR studies show that the silica in silica-rich glass phase dissolves in soda liquor, which indicates that silicon can be removed from illite after thermochemical activation (TCA) followed by alkali leaching. The formation of sodium aluminosilicates of Na 96Al 96Si 96O 384 and 0.95Na 2O · Al 2O 3 · 3.25SiO 2 · 4.79H 2O during alkali leaching may reduce the desilication to a great extent. Desilication tests after TCA show that the suitable activation conditions for illite are 1100∼1150°C and 90∼60 min. A desilication of 45% was obtained under the conditions for an ore sample bearing about 85% illite, 9% quartz and 5% muscovite.

Swelling Behavior of Black Liquor from Soda Pulping of Wheat Straw

The primary aim of this research work was to characterize the swelling properties of black liquor and their dependence on the temperature and gas composition of the combustion or gasification environment. The measurements were made using an industrial black liquor from soda pulping of wheat straw. The swelling measurements were carried out in a single droplet reactor. This paper presents data that show the influence of the reactor temperature and the gas composition on the swelling during devolatilization, and compares the swelling characteristics of a straw black liquor with similar published data on black liquors from kraft pulping of wood. Experiments were carried out in inert, oxiding, and gasifying environments, at temperatures from 500 to 900 °C. One interesting result was that the straw liquor swelled much more than most kraft or soda liquors from pulping of wood. Another result was that droplets subjected to hot gas atmospheres containing O2, CO2 and/or H2O(v) swelled less than those subjected to hot N2 atmospheres. The data obtained suggest that the straw soda black liquor would burn more rapidly than most kraft liquors from pulping of wood because of its high external surface area when swollen. This highly swelling liquor caused problems with fluidization when straw liquors were injected in a laboratory-scale fluidized bed gasifier.

Pulping of Whole Jute Plant (Corchorus capsularies) by Soda-Amine Liquor

Summary Pulping of whole jute plant is done by sodium hydroxide and ethylenediamine (EDA) or monoethanolamine (MEA) within 1 hour of cooking. The pulp yield is considerably higher than for the control soda and kraft pulps. Pulps obtained are better in physical properties as compared to kraft and soda pulps. The apparent density of soda-EDA pulps decreases with the increase of EDA in the soda liquor whereas the apparent density of soda-MEA pulps increases with the increase of MEA in soda liquor.

Alpha Rays Emitting Impurities in Ultra Pure Aluminum Evolution Through the Successive Refining Steps

Alpha rays are a major source of software errors in integrated circuits, especially in DRAM memories. A major aim of refining techniques used for the production of Ultra-pure aluminium alloys is therefore to eliminate radioactive impurities. This elimination was studied all along the refining steps from the ore (bauxite) to Ultra-pure aluminium. A major observation is that Radium isotopes accumulate in the caustic soda liquor, used for production of alumina from bauxite and in the cryolithic melt used for production of primary aluminium from alumina. Accumulated isotope Radium 228, which has a rather short half-life, disintegrates by β-emission to Thorium 228, which then transfers immediately to cathodic aluminium metal. This induces a strong disequilibrium in the decay chain of Thorium 232, and, as a result, more than 80 % of the total alpha-emission of Ultra-pure aluminium comes from alpha-decay of Thorium 228 and its daughters, which are not in equilibrium with Thorium 232. As a consequence, the content of Aluminium in U 238 and Th 232 (the only isotopes measured by GDMS or ICP/MS) can just give a rough order of magnitude of Alpha-emission, the Th 232 family being by far the most deleterious as regards software errors.

Reaction of Syringylglycerol-β-Syringyl Ether Type of Lignin Model Compounds in Alkaline Medium

Abstract Reactions of three kind of syringylglycerol- β-syringyl ether type model compounds under alkaline medium were investigated. Sinapyl alcohol and β-hydroxypropiosyringone were formed as phenyl propanoid moieties from syringylglycerol- β-(methyl-syringyl) ether 1 by the β-aryl ether cleavage under soda treatment, while only sinapyl alcohol was formed from syringylglycerol- β-syringyl ether 2. The formation of both two degradation products are quite interesting because there is no nucleophilic additives in soda liquor. A possible reaction mechanisms for the β-aryl cleavage of syringylglycerol-β-syringyl ether type is homolytical cleavage via quinone methide.

Jute stick lignin-based adhesives for particle boards

Soda lignin isolated from spent soda liquor of jute stick pulp was used for the preparation of lignin phenol formaldehyde resins. The adhesives were used to prepare jute stick particle boards. It was observed that phenol in phenol formaldehyde resin could be replaced up to a maximum of 50% by jute stick soda lignin.

THE INFLUENCE OF PENETRATION IN THE ALKALINE DELIGNIFICATION OF WOOD

The effect of various factors that might possibly influence the penetration of soda liquor into spruce wood has been examined. It was found that the rate of delignification was the same irrespective of the size of the sample, from a wood-meal of 0.005 mm. particle size up to a limiting chip thickness of about 10 mm. The density of the wood had no influence on the delignification other than that which would be expected from the higher original lignin content of the more dense wood. The presence of moisture in the chips was without result other than that of diluting the liquor, and the addition of wetting agents for facilitating the penetration rate was without significant effect.

The Aluminium Industry in Scotland

The production of aluminium is divided into five sections: mining, alumina manufacture, carbon electrode works, aluminium reduction works, and rolling mills; and the reasons determining the location of factories are set forth. The aluminium industry in Scotland includes the manufacture of alumina and carbon electrodes, and the electrolytic production of the metal. The latter is absolutely dependent on cheap regular supplies of electrical power, as approximately 26,000 kilowatt-hours are required for the manufacture of one ton of aluminium from alumina. The Burntisland Alumina Works of the British Aluminium Company are described. The process is a chemical one: the ore is ground and mixed in caustic soda liquor and digested under pressure and heat. Separation of solid impurities takes place, leaving a sodium aluminate liquor from which alumina hydrate settles out and is subsequently calcined. The plant includes grinding machines, digesters, decomposition tanks, rotary calciners, and accessory plant such as pumps and conveyers. A large supply of steam is necessary for the process. The Carbon Works at Kinlochleven supply the electrodes necessary for three factories in the north of Scotland, and a description is given of the various raw materials used and their conversion into baked electrodes by grinding, mixing whilst hot with a binder of tar and pitch, pressing under 2,000 tons pressure, and baking in producer-gas-fired furnaces. The electrolytic furnaces used to produce aluminium from alumina are similar in principle at the Foyers, Kinlochleven, and Lochaber factories, and as the latter is the latest factory erected in the north, a short description of the power system is given. Ultimately the power house will contain some 120,000 h.p. of generating plant. At present 33,000 kW. are installed. Each of the furnaces takes 40,000 amperes and is built of steel plate with a carbon lining forming a bath and serving as a cathode. The molten aluminium is deposited as a layer under the electrolyte, which is cryolite, and the carbon anode electrodes are consumed as the alumina is decomposed. The cost of the complete development at Lochaber will be in the neighbourhood of £4,500,000.

The Utilization of Waste Soda Liquors.

The Utilization of Waste Soda Liquors.

Method of making a cheap soda liquor, without crystallizing, for the use of the Turkey-red dyers

Method of making a cheap soda liquor, without crystallizing, for the use of the Turkey-red dyers