Caustic Extraction Research Articles

Colour removal from kraft mill caustic extraction effluent using calcium

Colour removal from kraft mill caustic extraction effluent using calcium

The use of an alga Chlorella pyrenoidosa and a duckweed Lemna perpusilla as test organisms for toxicity bioassays of spent bleaching liquors and their components

The toxicity of spent chlorination and caustic extraction liquors and several of their compounds has been verified using as test organisms two aquatic plants, an alga Chlorella pyrenoidosa and a duckweed Lemna perpusilla. The effect on acute toxicity of increasing numbers of chlorine substituents on the phenolic rings was reconfirmed, and trends relating toxicity to the number and type of oxygen-bearing substituents on the phenolic ring were also reported. The use of aquatic plants as test organisms in toxicity bioassays requires more refinement but ultimately could complement current bioassays using aquatic animals.

Evaluating Barite as a Source of Soluble Carbonate and Sulfide Contamination in Drilling Fluids

Summary Even when drilling-grade barites meet all current API specifications, they frequently are contaminated sufficiently with alkaline-soluble carbonate and sulfide minerals to cause serious drilling fluid problems. This paper describes in detail a new supplementary quality paper describes in detail a new supplementary quality control test that can identify many of these problem barites. Widespread use of this new test should facilitate a significant improvement in the quality of barite used in drilling operations. Introduction Barite is the overwhelming, choice as a material to build density in drilling fluids. In 1980, more than 3 million tons of barite were used in the U.S. for this purpose. A single barrel of high-density drilling fluid may contain more than 500 lbm of barite so that even small concentrations of impurities in barite can put significant contamination into the drilling fluid. Pure barite is barium sulfate (BaSO4) and is insoluble throughout the pH range encountered in drilling fluids. Commercial barites meeting current API specifications frequently contain from 10 to 30 wt% of a complex mixture of water-insoluble mineral impurities, but some of these impurities are soluble in alkaline drilling fluids. The cations from these solubilized impurities usually are precipitated as insoluble hydroxides and probably cause precipitated as insoluble hydroxides and probably cause little trouble. The anions, however, usually remain in solution, and when these anions are carbonates or sulfides, they can cause serious drilling fluid problems such as lost circulation, stuck pipe, and even problems such as lost circulation, stuck pipe, and even catastrophic loss of the well. Because of the complex composition of commercial barites, chemical analysis is of limited value in identifying barites that have the potential to cause serious drilling problems. Consequently, a simple screening test has been developed that can identify; those barites that have the potential to generate harmful quantities of soluble carbonate or sulfide ions. It is hoped that this test will be used widely by suppliers to select quality ores and by users to ensure receipt of quality material and to provide early warning of incipient field problems related to carbonate or sulfide ions. Guidelines for interpreting test results in terms of barite quality are highly dependent on specific drilling fluid formulations, and it is beyond the scope of this paper to suggest absolute standards that could be used to qualify a given barite for general use. This paper discusses (1) Exxon Co. U.S.A.'s field experience with carbonate and sulfide contamination from barite, (2) the sensitivity of a barite caustic extraction test to temperature, reaction time, and sodium hydroxide concentration, (3) test precision, and (4) recommended test use. A detailed test procedure is given in the Appendix. Field Experience with Carbonate and Sulfide Contamination From Impure Barite Carbonate Contamination The first clearly documented case of high levels of carbonate ion contamination derived from caustic-soluble materials in a commercial barite meeting current API specifications occurred in 1977 in an Exxon drilling operation at a Laterre well in the Lirette field in southern Louisiana. In addition to the usual rheological, filtration, and chemical tests, the drilling fluid at this well was being monitored by the Garrett Gas Train (GTT) method for carbonates, a new test in 1977. Excessive gel strengths were being encountered on this Laterre well but were not seen on an almost identical offset well. JPT P. 2371

Colour removal from kraft mill caustic extraction effluent using aluminum and iron

AbstractThe highly coloured compounds found in the caustic extraction effluents of kraft mill bleach plants can be removed by chemical reaction with trivalent metal ions (Me3+). At pH 2.8, these ions react stoichiometrically with carboxylic acid groups (A−) on the lignin compounds to form moderately soluble MeA3 salts. Above pH 2.8, hydroxyl ions compete with the A− groups to form highly insoluble hydroxy metal salts. Maximum colour removals of 99.6 and 98.8% were obtained for an effluent containing 12000 APHA colour units treated with 7 mol/m3 of Al3+ at pH 5.0 and Fe3+ at pH 3.3, respectively.

Structures of toxic constituents in kraft mill caustic extraction effluents from 13C and 1H nuclear magnetic resonance

Arguments based on 13C and 1H nmr spectroscopy are presented to elucidate the structures of 3,4,5- and 4,5,6-trichloroguaiacol, 12- and 14-monochlorodehydroabietic acid, and 12,14-dichlorodehydroabietic acid. These compounds were recently isolated and tentatively identified as major components toxic to fish in kraft mill caustic extraction effluents.

Decolourization of Kraft Mill Effluents by Magnesium Coagulation

Abstract A magnesium-plus-lime coagulation process incorporating magnesium recovery by sludge carbonation, recently developed for water treatment, has been tested for its application to decolonization of kraft mill effluents. Total bleached kraft mill effluent (BKME) after biological treatment and effluent from the first caustic extraction stage of a CEDED bleachery (T-20 effluent) were examined in the laboratory. Preliminary results of ongoing pilot scale testing of this unique treatment and recovery process on a simulated kraft waste are also presented. At the bench scale it was shown that a combination of low magnesium and low lime dosages can achieve better decolourization of kraft mill effluents than much greater amounts of lime alone. Colour removals of 90–95% were achieved using either fresh or recycled magnesium. Results of both laboratory and pilot plant studies showed that greater than 90% magnesium recovery can be attained with proper operation of the sludge carbonator.

Isolation and Identification of Constituents Toxic to Juvenile Rainbow Trout (Salmo gairdneri) in Caustic Extraction Effluents from Kraft Pulpmill Bleach Plants

Chemical constituents in effluent from the caustic extraction stage of the bleach plant at a western Canada kraft pulpmill were fractionated to identify factors responsible for their toxicity to juvenile rainbow trout (Salmo gairdneri). At all stages in the fractionation procedure bioassays were carried out to monitor toxicities of the isolated materials. Five toxic compounds, separated in a pure state from the effluent, were characterized by chromatography, spectroscopy, and chemical synthesis. The compounds and their 96-h median lethal concentrations (LC50) measured in static bioassays were: 3,4,5-trichloroguaiacol (0.75 mg/liter), 3,4,5,6-tetrachloroguaiacol (0.32 mg/liter), monochlorodehydroabietic acid (0.6 mg/liter), dichlorodehydroabietic acid (0.6 mg/liter), 9,10-epoxystearic acid (1.5 mg/liter).The same compounds were shown to be present in caustic extraction effluents collected from six other western kraft mills. For two samples, the concentration–toxicity graphs from bioassays of solutions containing only the pure toxicants in the amounts found by analysis were similar to those of the actual effluents produced by the mills. Concentrations of the toxic constituents in samples from six different mills were equivalent to 2.3–24 TU (toxic units), confirming that they are important factors in the toxicity of caustic extraction effluents.

A Study of Renovation of Pulp Waste Water Treatment of the Caustic Extraction Liquor with Lime

The present investigation was undertaken, as a part of the programme concerning with the renovation of kraft pulp waste water, to remove colored constituents (mainly lignin) in the coustic extraction liquor of bleached pulp by lime treatment and to make clear the effect of activated sludge treatment on lime treatment. Lime treatment of the caustic extraction liquor resulted in about 70% reduction in lignin. The lignin removal by lime treatment of the effluent treated with activated sludge became about 10% higher than that of untreated one. The COD components, showing no absorption at 280 nm, were almost removed by activated sludge treatment. Addition of seed crystals to the carbonation tank was effective for decreasing the SS in the effluent from the settling tank of calcium carbonate and the SS became about 80 ppm when the original SS in the carbonation tank was more than 15000.

COMPARISON OF CHARACTERISTICS OF SOFTWOOD AND HARDWOOD SULPHITE PULPS DURING THE BLEACHING PROCESS

Softwoods (spruce+fir, and fir only) and hardwoods (mixed hardwood, and birch only) unbleached sulphite paper grade pulps were bleached with three-stage processes (chlorination, caustic extraction, hypochlorite) and a comparison was made on behavious of softwood and hardwood sulphite pulps during the bleaching.1) In comparison with softwood unbleached sulphite of the same Sieber number, hardwood sulphite pulps were lower in the bleaching loss (Fig. 1), and higher in brightness of bleached pulp (Table 1 and 2) and consumption of caustic soda (Fig. 2). The yields of boths oftwood and hardwood bleached pulps were lower than those expected from their lignin contents calculated from Sieber number of unbleached pulps.2) The loss of xylan and mannan in pulps during bleaching process were very small and total amounts of them were about 0.2% in both softwood and hardwood unbleached pulps (Sieber number about 52) (Table 5). The dissolved carbohydrate materials were mainly xylan in the case of hardwood pulp, while considerable amount of mannan was found in addition to xylan in the case of softwood pulp. Considerable amounts of uronic acids were also removed during these treatments and the loss mounted to 20-30% of original uronic acid contents of both softwood and hardwood unbleached sulphite pulps (Table 3 and 4).3) Lignin contents of unbleached pulps were determined UV-absorptiometrically on phosphoric acid solution. It was shown that the lignin content of the herdwood unbleached sulphite pulps was about 20% less than that of softwood unbleached sulphite pulps of the same Sieber number (Fig. 5 and 6). It seems that the difference in the yield of softwood and hardwood bleached sulphite pulps was mainly due to the difference in the lignin contents.4) The amounts of lignin eliminated from unbleched sulphite pulps were determined UV-absorp-tiometrically in the bleaching process. Lignin in unbleached hardwood sulphite pulp was easier to remove than that of softwood pulp during caustic extraction after chlorination (Fig. 8) and hypochlorite bleaching. Considerable amount (about 35%) of the former was also removed even by 1% NaOH extraction at 20°C for 1 hr. (Fig. 9)

COMPARISON OF CHARACTERISTICS OF SOFTWOOD AND HARDWOOD SULPHITE PULPS DURING THE BLEACHING PROCESS

Hardwood unbleached sulphite pulps consumed more caustic soda than softwood pulps during caustic extraction in bleaching process. This investigation concerns this problem.The results of conducto-and potentiometric titrations of spent caustic extraction liquors (Fig. 1), and gas-chromatographic analysis of the same liquors (Fig. 7) and hydorolysates of these pulps show that the difference in the consumption of caustic soda is due to the difference of acetyl group contents in the both unbleached pulps. Acetyl group contents of hardwood unbleached sulphite pulps (47-55% of total cooking yield) are 0.6-1.0%, while only about 0.1% in softwood unbleached pulps.In the bleaching process, these acetyl groups in unbleached sulphite pulps were not or little removed by chlorination (Fig. 5 and 6), but most parts were removed by caustic extraction. Therefore, acetyl groups cannot be found in bleached sulphite pulps.The acetyl groups in unbleached sulphite pulps were nearly completely removed by 1% NaOH extraction (20°C, 1 hr.) or bisulphite-soda cooking. By those processes the amotnts of caustic soda consumed in bleaching of hardwood unbleached sulphite pulps decreased greatly to that of softwood unbleached sulphite pulps of the same Sieber number (Table 1, Fig. 3, 4 and 8).It seems that the acetyl groups combine with xylan existing in amorphous region of unbleached sulphite pulps.

Effects of Fiber Bonded Area and Hemicelluloses on Physical Properties of Paper

Birch bleached sulphite pulps extracted with 1-5% sodium hydroxide solutions were beaten by Lampen mill or Tappi standard test beater. Beating rate and tensile or bursting strengths of the pulp at the equal freeness decrease with the amount of hemicelluloses extracted (Table 1, Fig. 1 and 2). The reason seems to be that water retention value of pulp beaten at the equal freeness and fiber bonded area in the dried sheet (shown as specific scattering coefficient) decrease with the amount of hemicelluloses extracted (Fig 3). However, the water retention value, especially specific scattering coefficient relates closely with tensile or bursting strengths of the sheet, irrespective of the amount of extracted hemicelluloses (Fig. 4 5 and 6).The pulp beaten in aluminium sulphate solution is poor in beating rate and bursting strength compared with the pulp beaten in water. On the other hand, the uronic acid-rich pulp bleached with sodium chlorite (Table 2) is easier to swell by beating and higher in bursting strength at the equal freeness compared with the pulps bleached by a conventional 3 stages process (chlorination, caustic extraction, hypochlorite bleaching). In all these pulps, however, specific scattering coefficient relates with the tensile or bursting strengths (Fig. 7 and 8). Speciffic scattering coefficient relates also with air permeability (Fig. 9 and 10).The tearing strength and the wet tensile strength of the pulps treated with sodium hydroxide solutions are higher than those of the original pulp at the equal specific scattering coefficient (Fig. 11 and 12) This result shows probably that the bonding strengths at the equal bonded area of these pulps are not invariably constant.Sheet density does not relate with specific scattering coefficient in the case of pulps varied in hemicellulose contents (Fig. 13).

The Influence of Micronaire Fineness and Prior Treatments on the Cyanoethylation of Cotton

Fiber fineness, as measured by the Micronaire, and prior treatments have been found to be important factors in determining the rate and extent of cyanoethylation of cotton. Fineness was found to be a good index of the rate of reaction for both raw and pressure- boiled cotton fibers. Prior treatment of yarn by ethanol extraction, pressure boiling with 2% caustic ethanolamine extraction, and mercerization—both slack and at constant length—affected the rate of cyanoethylation and the rot resistance of the product.