scholarly journals Sequential In-Situ Carbonation Process for the Preparation of Hand Sheets with Waste Lime Mud

Reactions ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 3-15
Author(s):  
Ramakrishna Chilakala ◽  
Thriveni Thenepalli ◽  
Seongho Lee ◽  
Hong Ha Thi Vu ◽  
Lai Quang Tuan ◽  
...  
Keyword(s):  
Paper Industry ◽  
Hydration Process ◽  
Smelting Process ◽  
Green Liquor ◽  
Carbonation Process ◽  
White Liquor ◽  
Lime Mud ◽  
Different Temperatures ◽  
Sample Purification ◽  
Process Elements

In the pulp and paper industry, the white liquor obtained from the causticizing green liquor in the smelting process mostly contains NaOH and Na2S. These chemicals are returned to the digester for reuse in the pulping process. The lime mud (LM) material is obtained from the reaction of the causticization process in paper industries. It is mainly composed of CaCO3; it appears with a green color with a high moisture content; and it has a small proportion of impurities such as non-process elements, for example Fe, Na, Mg, Al, Si, P, and S oxides and other toxic metals. This lime mud has poor whiteness with less efficiency due to its contaminated with impurities. The recycling or reutilizing process for lime mud and solid wastes are minimizing its toxic effect on the environment. The present study proposed to improve the whiteness of the waste lime mud by the calcination and hydration process at high temperatures and reutilizing it for hand sheets, making the process improve the paper brightness. In this study, we used a lime mud sample for calcination at 1000 °C and 1200 °C for 2 h and hydration at different times (3–24 h) with different temperatures (30–80 °C) and measured the powder whiteness and hand sheet brightness. The results indicated that after the calcination and hydration process, the lime mud sample whiteness was improved and that re-utilization with pulp for making hand sheets also can improve the paper brightness. It can be concluded that waste lime mud sample purification and the re-utilization process are more advantageous in paper industries.

scholarly journals Pembuatan PCC (Precipitated Calcium Carbonate) Menggunakan Bahan Baku Lime Mud Dengan Metode Kaustik Soda

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Gina Maulia
Keyword(s):  
Calcium Carbonate ◽  
Precipitated Calcium Carbonate ◽  
Green Liquor ◽  
White Liquor ◽  
Lime Mud

Recausticizing merupakan proses pengolahan green liquor menjadi white liquor sebagai produk utama dan lumpur kapur (lime mud) sebagai produk samping. Lime mud sebagai produk samping memiliki kandungan CaCO3 yang cukup tinggi sehingga memungkinkan untuk dimanfaatkan menjadi produk yang bernilai jual lebih tinggi. Penelitian ini bertujuan untuk memanfaatkan lime mud sebagai bahan baku pembuatan PCC (Precipitated Calcium Carbonate) yang memiliki nilai jual lebih tinggi. Penelitian pembuatan PCC ini menggunakan metode kaustik soda dengan variasi dosis HNO3 1 M, 3 M, 5 M, 7 M, 9 M, 11 M, dan 12 M kemudian ditambahkan Na2CO3 untuk pembentukan PCC. Berdasarkan hasil penelitian, didapatkan dosis optimum yaitu pada konsentrasi HNO3 12 M dan Na2CO3 2 M dengan nilai rendemen 97.1 % dan kemurnian 99.57 % yang menunjukkan bahwa hasil tersebut sesuai dengan standar PCC.

New challenges regarding nonprocess elements in the liquor and lime cycle

TAPPI Journal ◽  
2015 ◽  
Vol 14 (7) ◽  
pp. 421-429
Author(s):  
MARTA BIALIK ◽  
ANNA JENSEN ◽  
MIKAEL AHLROTH
Keyword(s):  
Common Knowledge ◽  
Poor Performance ◽  
Green Liquor ◽  
Lime Kiln ◽  
White Liquor ◽  
Lime Mud ◽  
Sampling Campaign ◽  
Rules Of Thumb ◽  
The Common ◽  
Process Solutions

Optimal performance of the green liquor plant, recausticizing plant, and lime cycle is vital for adequate white liquor availability and quality as well as for a mill’s energy efficiency. Recently, various problems in the liquor and lime cycle have been frequently reported by our industrial partners, including poor performance of green liquor filters or sludge filters, decreased filterability of lime mud, increased lime kiln dead load, and poorquality white liquor. Those problems are most likely caused by an accumulation of nonprocess elements in the liquor and lime cycle due to increased mill closure, increased use of biofuels, or both. Data from the literature and earlier studies have been analyzed with regard to the occurrence and concentration of nonprocess elements in various process streams, including filtered green liquor, green liquor sludge, lime mud, and white liquor. The mineral forms in which nonprocess elements often precipitate were also studied, together with the common knowledge and rules of thumb used by mills for dealing with the problems. The literature data are compared with the newest analytical results from a sampling campaign involving several mills with varying process solutions with respect to nonprocess elements. The consequences and possible recommendations for the mills are presented.

scholarly journals Modeling, simulation, and analysis of a reactor system for the generation of white liquor of a pulp and paper industry

2011 ◽  
Vol 54 (1) ◽  
pp. 197-206 ◽  
Author(s):  
Ricardo Andreola ◽  
Regina Maria Matos Jorge ◽  
Onélia Aparecida Andreo dos Santos ◽  
Luiz Mario de Matos Jorge
Keyword(s):  
Paper Industry ◽  
Pulp And Paper Industry ◽  
Pulp And Paper ◽  
Reactor System ◽  
Modeling Simulation ◽  
White Liquor

scholarly journals Hydration Features of Composite Binding Material with High-Dose Copper Tailings

2021 ◽  
Vol 45 (1) ◽  
pp. 17-24
Author(s):  
Yang Wang ◽  
Hanxi Wang ◽  
Linwei Yang ◽  
Li Qian
Keyword(s):  
Hydration Process ◽  
High Dose ◽  
Mass Concrete ◽  
Copper Tailings ◽  
Granulated Blast Furnace Slag ◽  
Binding Material ◽  
Different Temperatures ◽  
Hydration Model ◽  
Center Particle ◽  
Parameter Values

Based on Krstulovic-Dabic model, this paper modifies the center particle hydration model according to the features of copper tailings, and then simulates the hydration process of cement-based composite binding system mixed with copper tailings. The hydration exothermic features were analyzed under different dosages, and different temperatures. Then, the simulated parameter values of the hydration process were compared with those measured in experiments. The results show that: the mixing of copper tailings powder can reduce the hydration heat release and slow down hydration rate of the composite binding material, and improve the thermal performance of the concrete; the prepared copper tailings powder is active enough to replace fly ash and ground-granulated blast furnace slag (GGBS) as cement admixtures; When the dosage surpasses 40%, the copper tailings can be applied to mass concrete projects.

Cleavage of acetyl groups from northeast hardwood for acetic acid production in kraft pulp mills

TAPPI Journal ◽  
2013 ◽  
pp. 57-67 ◽  
Author(s):  
RAVIKANT PATIL ◽  
JOSEPH M. GENCO ◽  
HEMAND PENDSE ◽  
ADRIAAN VAN HEININGEN
Keyword(s):  
Acetic Acid ◽  
Kraft Pulp ◽  
Ion Concentration ◽  
Alkali Concentration ◽  
Extraction Temperature ◽  
Pulp Mills ◽  
Hydroxide Ion ◽  
Green Liquor ◽  
White Liquor ◽  
Kraft Pulp Mills

This study identified the optimum conditions for cleavage of acetyl groups from wood hemicelluloses for possible conversion to salts of acetate or to acetic acid in kraft pulp mills. Acetyl groups in wood hemicelluloses can be hydrolyzed by either OH- (hydroxide) or H+ (hydronium) ions. Experimental data are presented for the extraction of industrial northeast hardwood chips using alkali streams that are available in the kraft pulp mills: caustic, green liquor, and white liquor. The effects of extraction time, chip soaking temperature, alkali concentration, and extraction temperature on cleavage of acetyl groups were investigated. Soaking at elevated temperature was found to be more effective than no soaking or soaking at room temperature. The rate of cleavage of acetyl groups from wood hemicelluloses was proportional to the initial hydroxide ion concentration in the liquor. Both white liquor and 0.5 N sodium hydroxide had higher rates of hydrolysis of acetyl groups compared to green liquor, which contained fewer hydroxide ions. The initial hydroxide ion concentration in the liquor also determined the mechanism by which acetyl groups were hydrolyzed from the hemicellulose backbone. If the extraction liquor contained excess hydroxide ions, then most acetyl groups were directly hydrolyzed from the xylan polymer to form sodium acetate, and the xylan remained in the wood, provided the temperature was low. The extraction temperature had a negligible effect on rate of cleavage of acetyl groups if the liquor contained excess hydroxide ions.

scholarly journals Localised corrosion of super duplex stainless steel in synthetic NaOH-Na2S solution at different temperatures

2021 ◽  
Author(s):  
Carlos Eduardo Rondón-Almeyda ◽  
Lina María Sierra-Serrano ◽  
Mauricio Rincón-Ortiz
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Pitting Corrosion ◽  
Paper Industry ◽  
Pulp And Paper Industry ◽  
Corrosion Mechanism ◽  
Super Duplex Stainless Steel ◽  
Pitting Corrosion Resistance ◽  
Different Temperatures ◽  
Potentiodynamic Polarisation

The pitting corrosion resistance of the UNS S-32760 super duplex stainless steel (SDSS) in synthetic NaOH-Na2S solution at different working temperatures of 25, 50, and 70°C has been evaluated in the current investigation to assess the alloy behaviour under the caustic environments used in the pulp and paper industry. The temperature effect on pitting (Ep) and repassivation (Erp) potentials was studied with the Cyclic Potentiodynamic Polarisation (CPP) technique according to the ASTM G61. Results demonstrated that pitting corrosion is prone to occur when increasing alloy temperature since both pitting and repassivation potentials lean towards more negative values while the repassivation zone is reduced. Furthermore, the morphology of the found pits was determined using Scanning Electron Microscopy (SEM). The pitting corrosion mechanism for the studied super duplex stainless steel under the exposed conditions was introduced. The thiosulphate ion is attributed to be responsible for the initiation of the localised corrosion.

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