Pulp Slurry Research Articles

Impact of dissolved organic matter in D0- and AD0-stages in bleaching of birch kraft pulp

Abstract To be able to charge a correct amount of chlorine dioxide in the D0-stage, a pulp mill needs good control of the bleaching process and good sensors to keep the variability of the bleaching result on an acceptable level. It is also important to include the bleaching agent demand from the dissolved matter in the pulp slurry. If this is done correctly, over- or undercharging of bleaching agents can be reduced, which lead to lower bleaching chemical cost, lower polluting emissions and higher pulp quality. Our previous research has shown that the dissolved organic carryover from the O2-stage varies significantly when bleaching softwood kraft pulp. The present study investigated the corresponding impact in the case of bleaching of birch pulp. Different mill configurations and process conditions have been simulated in laboratory trials, including proceeding A-stage treatment, different degrees of washing before and between the stages, and a comparison of the effects of recycled and non-recycled wash filtrates. The results have confirmed the significant impact of the dissolved organic matter, and the knowledge which have been generated can be used to understand how measurement and control concepts can be developed to improve the pulp quality control and to decrease production cost.

Cationic cellulose nano-fibers (CCNF) as versatile flocculants of wood pulp for high wet web performance

In recent years, cellulose nano-fibers (CNF) have been regarded as renewable, promising reinforcer to enhance the strength property of paper products. In this paper, the roles of cationic cellulose nano-fibers (CCNF) as versatile flocculants of wood pulp and fines in pulp slurry for high wet web performance have been studied. It was found that CCNF can induce significantly flocculation (CCNF-Fines complex) in pulp slurries. The mechanical properties of wet web can also be improved by the addition of CCNF. The study demonstrated that CCNF can act as effective flocculants of fines and form CCNF-Fines complex for improved wet-web strength, in addition, CCNF has little effect on the dewatering rate of wet-web. CCNF is more beneficial to the wet web performance when it is in higher charge density. The research paves a way to further study the comprehensive application of CCNF in the wet-web making process for high performance.

Horseradish and potato peroxidase biobleaching of mixed office waste paper

Mixed office waste (MOW) pulp was biodeinked with crude enzyme extracted from Penicillium citrinum NCIM-1398. Crude enzyme dose was charged having activities of endo β-1,4-glucanase 6I U/g, xylanase 876.19 IU/g, and amylase 26.53 IU/g. The present study aimed to bleach the biodeinked MOW pulp with 3% H2O2 in the presence of a stabilizing agent viz. 0.1% ethylenediaminetetraacetic acid (EDTA) and 0.1% magnesium sulfate (MgSO4), which improved the pulp brightness up to 4.2% and the ERIC value was reduced by 24.1%. The residual H2O2 left in the pulp slurry after bleaching was subjected to peroxidase treatment using enzyme dose 0.017 U/g at 20 °C for 3 h at 200 rpm. Horseradish peroxidase reduced residual H2O2 in the pulp slurry from 0.30 to 0.05 g/L and improved the brightness of pulp to 88.1%, while the ERIC value was reduced by 20.9%. Potato peroxidase reduced residual H2O2 from 0.30 to 0.04 g/L, reduced the ERIC value by 30.9%, and improved the brightness to 89.2%. Peroxidase treatment was not only observed to consume the residual hydrogen peroxide left after the bleaching stage but also may come up as eco-friendly technology to recycle MOW paper as writing printing grade paper.

Slurry Flow and Erosion Prediction in a Centrifugal Pump after Long-Term Operation

After long-term operation, the material loss due to slurry erosion often leads to significant changes in the impeller geometry. This change can, in turn, affect the flow characteristics and the erosion mechanism in a centrifugal pump. To investigate this matter, we consider two geometric models based on a prototype stainless steel impeller, which failed due to huge erosion problems from the pulp slurry. These two models are different in the degree of wear, with one model at the pre-erosion stage and the other with worn blades. For both models, the flow characteristics have been obtained in the Eulerian reference frame by means of the SST k-ω model. Then, in order to determine the erosion patterns, the particles have been tracked in the Lagrangian reference frame. In this way, the influence of the flow characteristics on the erosion patterns has been analyzed. Results show that the geometric variations greatly affect the flow characteristics, and consequently the erosion patterns. Particularly, it has been found that the clearance flow plays a significant role in defining erosion characteristics, such as erosion distribution, areas, and rates. Interestingly, the simulation results for current study show that the erosion rates after long-term operation greatly decrease near both the outlet edge and the blade bottom. It follows also that for accurate erosion predictions, these geometric variations have to be considered in the numerical model. This paper provides a better understanding of the complex erosion mechanism in centrifugal pumps, which can help to reduce the wear in future designs.

ОПЫТ ЭКСПЛУАТАЦИИ ЦЕНТРОБЕЖНЫХ ОДНОСТУПЕНЧАТЫХ НАСОСОВ В АКЦИОНЕРНОЙ КОМПАНИИ «АЛРОСА»

When mining diamond-bearing raw materials and further extracting diamonds from it in the joint-stock company ALROSA, which is a city-forming enterprise in the north-east of the Russian Federation, various pumping equipment is used, in particular, centrifugal single-stage pumps. In the present work, it is noted that the least reliable in terms of absence of failures of centrifugal single-stage pumps used in the joint-stock company ALROSA are the impellers, seals and bearing assemblies. Using linear correlation and regression analysis, it was found that the durability of the seals and bearing assemblies of the investigated pumps largely depends on the durability of their impellers. In the course of research, it was found that unbalancing the pump rotor due to excessive hydroabrasive wear of the impeller also leads to deformation and fracture of the shaft. In general, residual deformations and destructions are characteristic of the shafts of domestic pulp pumps of GrAT, GrT and Gr types. The most loaded sections of shafts of centrifugal single-stage pumps are installed. The most effective from the point of view of application among the pulp (ground, slurry and sand) pumps are pulp pumps of the Finnish company «Metso». When working on highly mineralized water (brines), the «X» type pumps have proven to be the best among centrifugal single-stage pumps.

Flexural, water absorption and wear responses of green composites from bio-resources

This research was carried out to produce corn husk fibre reinforced recycled waste paper-based composites using natural rubber as a binder. The paper pulp was obtained by soaking waste paper in water for 24 hours after which it was ground. The paper pulp slurry was sun dried for five days followed by pulverizing and sieving. Corn husk was turned to fibre strands that were cut to 5 mm so as to obtain short fibres. Varying mass of the recycled waste paper and corn husk fibre were blended with constant volume of natural rubber to produce the various samples. The mixtures were thoroughly mixed and poured into the moulds for the development of flexural and wear samples after which they were compacted using the laboratory compacting machine. The compacted composites in their green form were removed and allowed to further cured under sunlight for 10 days before been subjected to flexural, wear and water absorptivity tests. From the results, flexural properties were enhanced between 4–8 wt% corn husk fibre addition while wear and water absorption properties were enhanced at 10 wt% corn husk fibre addition. This composite can be used as partitioning board, ceiling sheets as well as counter-tops applications.

Usage of hydrocyclones and thickening plates to densify pulp slurry before leaching

Usage of hydrocyclones and thickening plates to densify pulp slurry before leaching

Starch Derivatives that Contribute Significantly to the Bonding and Antibacterial Character of Recycled Fibers.

The objective of the current research was to fabricate and explore the ability of a renewable resource-based paper strength agent to enhance fiber–fiber bonding and introduce antibacterial properties to recycled fiber paper sheets. The agent corn starch, was modified with diethylenetriamine pentaacetic acid (DTPA), complexed with chitosan, and added to recycled furnishes to provide a plethora of hydrogen bonding sites predicated by acid groups, hydroxyls, and amines. The goal was two-fold: (1) to not only increase interfiber bonding, but (2) afford antibacterial character. The modified corn starch was characterized in previous work by thermal gravimetric analysis, differential scanning calorimeter, and Fourier transform infrared spectroscopy. The recycled pulp slurry was mixed with a ∼1.5% modified starch/chitosan agent before manufacturing a two-dimensional paper substrate that was subjected to mechanical testing. The burst, STFI compressive strength, tensile, and interfiber bonding strength increased 48.8, 49.5, 49.9, and 176%, respectively, while significantly increased gloss was obtained despite slightly diminished tear and roughness. The antibacterial character of these substrates was confirmed by the substrates displaying a 97% bacteria kill rate.

Evaluation of Flocculation Property of the Pulp Slurry Influenced by Chemical Addtives Using HYSTAP

Evaluation of Flocculation Property of the Pulp Slurry Influenced by Chemical Addtives Using HYSTAP

Production of cellulose nanofibers using phenolic enhanced surface oxidation

In this study we demonstrate that lignin monomers formed as byproducts of pulping or bioprocessing of lignocellulosic biomass is an effective enhancer to oxidize cellulose surfaces with ozone for the production of cellulose nanofibers (CNF). Never dried softwood pulp with minimum mercerization was enzymatically treated leading to a homogeneous pulp slurry with a higher reactivity. The slurry was oxidized by ozone gas in the presence of syringic acid, a lignin degradation model compound, as an oxidation enhancer at room temperature and pH 11. Transmission electron microscopy (TEM) observations showed that stable CNF bundles with 3–10nm widths and lengths >100nm were obtained after ultrasonication of the oxidized product in water. Extensive characterization of the new CNF films revealed the nanofibers had carboxylate content similar to conventional carboxylated cellulose prepared by TEMPO-mediated oxidation. Based on NMR spectra, chemical conversion of the syringic acid during oxidation is proposed.

Effect of enzyme beating on grinding method for microfibrillated cellulose preparation as a paper strength enhancer

Hardwood bleached Kraft pulp was treated with an endoglucanase prior to Valley beating. The Valley-beaten pulp slurry was further ground with a particle grinder in order to evaluate the effect of enzyme beating on preparation of microfibrillated cellulose (MFC). The time required to make 100 mL Canadian Standard Freeness pulp slurry was greatly reduced by enzyme pre-treatment. The viscosity of the enzyme-beaten MFC slightly increased with grinder pass number; however, the rate of change in viscosity was much lower than that of non-enzyme-beaten MFC. The crystallinity of MFC decreased with grinder pass number for both cases. The drainage of the pulp slurry containing enzyme-beaten MFC was higher than that of the pulp slurry containing non-enzyme-beaten MFC. Further, the enzyme-beaten MFC subjected to the 10 passes grinding had the same tensile index as the MFC subjected to the 15 passes grinding. Thus, the mechanical energy for MFC manufacturing can be greatly reduced with enzyme beating.

Effects of shrimp chitosan on the physical properties of handsheets

The effects of shrimp chitosan as an additive were determined on the physical properties of handsheets, especially: their brightness, opacity, surface roughness and surface water absorptiveness. Commercial, hardwood, bleached kraft pulp was beaten to attain 390 mL Canadian standard freeness and then made into four sets of handsheets by mixing each part of the beaten pulp slurry with shrimp-chitosan solution to obtain 0.00%, 0.25%, 0.50% and 0.75% (oven dry weight (o.d. wt.) of pulp), respectively, in accordance with standard test methods. All the sets of handsheets were conditioned for 1 wk and then tested for their mechanical and physical properties at 50 ± 2% relative humidity and 23 ± 1 °C. The results indicated that even though there were some substantial decreases in some physical properties of shrimp-chitosan-treated handsheets (brightness, surface roughness and surface water absorptiveness), their opacity was slightly increased. Most of the mechanical properties of shrimp-chitosan-treated handsheets such as the bursting index, folding endurance, tensile index, modulus of elasticity and tensile energy absorption were greatly increased with the addition of shrimp chitosan at 0.25% o.d. wt. of pulp to 0.50% o.d. wt. of pulp. However, there was no effect on the tearing strength by adding shrimp chitosan to the handsheets.

Complete nanofibrillation of cellulose prepared by phosphorylation

In this work, we prepared phosphorylated pulp with a phosphorous content of 1.23 mmol/g by adding an aqueous solution of NH4H2PO4 and urea to softwood pulp sheets followed by drying and curing with hot air and obtained cellulose nanofibers (CNFs) with a uniform width of 3–4 nm in approximately 100% gravimetric yield by high-pressure homogenization of the phosphorylated pulp slurry. After phosphorylation, no significant decrease in the pulp recovery ratio was observed, and the viscosity-average degree of polymerization of phosphorylated pulp was almost equal to that of the original pulp. In addition, the crystal structure and crystallinity index were almost unchanged during phosphorylation. The obtained phosphorylated CNF dispersion was highly transparent, and the maximum total light transmittance was nearly 100% when the CNF content was 0.2 wt%. The maximum viscosity of the CNF dispersions was nearly 10–100 times greater than that of conventional thickeners. Furthermore, we found that not only insufficient but also excessive phosphorylation negatively affected the gravimetric yield, transparency and viscosity.

Improving the efficiency of hydrogen peroxide bleaching of chemimechanical pulp by continuous replenishment of bleaching chemicals

Hydrogen peroxide (H2O2) is commonly used to bleach chemimechanical pulp. A decrease in the concentrations of the bleaching reagents throughout the bleaching process results in low bleaching efficiencies. In this study, chemical solutions were continuously added into the pulp slurry during the bleaching process to maintain constant concentrations of H2O2 and total alkali in the bleaching system to improve bleaching efficiency. The results showed that when the H2O2 and total alkali concentrations were maintained at 4.5 g/L and 0.79 g/L, respectively, for 50 min, the bleaching efficiency reached 16.79 (Δ% ISO brightness/Δ% H2O2 consumed [on ovendry pulp]), which was significantly higher than 7.38 obtained by using the high-consistency bleaching method. The results confirmed that continuous replenishment of chemical solutions into the bleaching system to maintain the constant chemical concentrations improved the efficiency of H2O2 bleaching of the chemimechanical pulp.

Chitosan-Based Reagents Endow Recycled Paper Fibers with Remarkable Physical and Antimicrobial Properties

The aim of the current work was to develop and study a paper additive system that endows recycled paper fibers with strong mechanical and antimicrobial properties. Five different types of modifying agents including succinic acid, carboxymethyladipic acid, butanetetracarboxylic acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid (DTPA) were reacted with soy flour. Approximately 2% modified soy flour additive by mass relative to a old corrugated container (OCC) pulp slurry was mixed before generating a two-dimensional hand sheet for physical testing. DTPA-modified soy-flour-treated OCC pulp displayed better tensile relative to the results from the use of other modifying agents. Soy flour was treated with different DTPA concentrations, times, temperatures, and pH values to determine the optimal modification reaction conditions. Afterward, the DTPA–soy flour was complexed with chitosan to decrease the biodecomposition of soy protein, improve its incorporation into an OCC matrix, and ...

超高分子量ポリエチレンオキサイド（PEOⓇ） 使用による紙料濃度の高濃度化

超高分子量ポリエチレンオキサイド（PEOⓇ） 使用による紙料濃度の高濃度化

양이온성 지방산아민 벌키화제를 이용한 저밀도 종이 제조 (3) - 펄프 고해도 및 벌키화제 처리 농도에 따른 영향 -

The effects of pulp beating degree and bulky promotor concentration on the properties of handsheet including a bulk and strength have been investigated during manufacturing of low density paper (high bulk paper) with cationic fatty acid bulky promotor. It was found that paper bulk increased with increasing cationic fatty acid bulky agent concentration, while tensile strength decreased. On the other hand the opacity of handseets also increased with increasing cationic fatty acid bulky agent concentration, while brightness decreased slightly. With increasing pulp beating degree, paper bulk as well as tensile strength increased, while opacity decreased. Brightness did not show a significant difference with increasing pulp beating degree. The highest bulk and strength values were observed when 1.5% (SwBKP) and 2% (HwBKP) of bulky promotor was treated into the 450 mL CSF pulp slurry.

KAJIAN PEMANFAATAN BUAH NAGA MERAH (Hylocereus polyrhizus) DAN MANGGA (Mangifera indica Linn) DALAM PEMBUATAN FRUITLEATHER

ABSTRACTFruit leather is kind of processed food products derived from the dried pulp slurry until the water had 10-15%. The criteria for manufactured of fruit leather was determined by the sugar, fiber and acid. The fruit hadused was red dragon fruit, which had a high fiber. The study was aimed to get the best combination of reddragon fruit (Hylocereus polyrhizus) and mango (Mangifera indica Linn). The research used a CompleteRandomized Design (CRD) with 5 treatments and 3 replications. The treatments were N4M0 (Red dragon fruit100% : mango 0%), N3M1 (Red dragon fruit 75% : mango 25%), N2M2 (Red dragon fruit 50% : mango 50%),N1M3 (Red dragon fruit 25% : mango 75%) and N0M4 (Red dragon fruit 0% : mango 100%). The dataobtained were analyzed statistically using Anova and DNMRT at 5%. The results show that ratio of reddragon fruit and mango by affected the degree of acidity (pH), water, ash, crude fiber and total sugar contentsas well as organoleptic test. The best treatment of fruit leather from this research was N1M3 which had water11,00%, ash 0,63%, degree of acidity (pH) 5,36, crude fiber 7,34%, total sugar 59,57%, reddish yellow color,a little bit red dragon fruit flavour and mango flavour, sweetness taste, springy texture and overall assesmentof fruit leather was preferred by the panelist’. Key words: Fruit leather, red dragon fruit and mango.

Preparation and Evaluation of Peach-Soy Fruit Toffees

The peach-soy toffee was prepared from different blends of peach pulp and soy-slurry. The peach pulp and soybean slurry were blended in the ratios of 100:0, 95:5, 90:10, 85:15, 80:20, 75:25 and 70:30. The product was prepared as per the standard recipes and was stored for four months to ascertain changes in physico-chemical and sensory characteristics. The analysis of toffees revealed significant differences among different blends. In toffees, maximum moisture content of 17.17 per cent was recorded in B1 (100:0:: P:S). The highest TSS and titratable acidity of 12.23 0B and 1.62 per cent were recorded in B1 (100:0:: P:S), respectively. Reducing sugar (37.95 per cent) and total sugar (64.93 per cent) were also found to be highest in B1 (100:0:: P:S). It was observed that protein and fat contents of 3.43 and 8.66 per cent were recorded highest in B7 (70:30:: P:S), respectively, whereas highest ascorbic acid content of 21.80 mg/100 g was recorded in B7 (70:30:: P:S). Sensory evaluation of toffees revealed that the highest score of 8.30 was recorded in B4 (85:15:: P:S) and lowest score of 6.01 was recorded in B7 (70:30:: P:S). In general there was an increase in TSS, acidity and sugars and decrease in protein, fat and ascorbic acid contents and all sensory attributes during four months storage in different blends of toffees.

Repeated homogenization, a route for decreasing the energy consumption in the manufacturing process of carboxymethylated nanofibrillated cellulose?

Energy-efficient manufacturing is a requirement for the large-scale production of nanofibrillated cellulose systems. Today, most strides involve the development of new physicochemical pre-treatment processes or invention of new or further-development of existing mechanical delamination processes; these approaches are often costly. In this communication, it was shown that significant reduction in energy consumption (~30–50 %) of the nanofibrillated cellulose (NFC) manufacturing process is possible by the wise employment of existing machinery and processes—without deterioration of the attractive properties of the NFC product. The suggested approach has further the additional advantage of increasing the yield of nanofibrillation, robustness of the manufacturing process, and increasing the out-put of the process. These notions can lead to significant energy savings in the NFC production. The novel manufacturing protocol involved repeated homogenization of the pulp suspension at low (~400 bar) applied homogenization pressures (as compared to those currently applied, ~1700 bar). It was hypothesized that this manufacturing protocol leads to a more homogeneous and effective shearing of the fibres, than is achievable by one time homogenization of the pulp slurry at high applied pressures. The investigations further showed that there exists an apparent yield of fibrillation (of about 40 %), above which the rheological properties of the NFC systems and the mechanical properties of the resulting NFC films remain unaffected. This observation [which is in accordance to published observations by e.g. Fall (2013)] can be employed to reduce the specific energy consumption in the NFC manufacturing process. Finally, the investigations also showed that the route that is used for dilution of concentrated NFC systems can significantly alter the properties of resulting NFC-films. It was postulated that a protocol based on the severe shearing of the NFC suspension (prior to NFC-film formation), e.g. by high pressure homogenization, can lead to a more homogeneous and better fibrillated system, which in turn might lead to the overestimation of the actual properties of the studied NFC system.