Process Liquors Research Articles

Carbonation and modeling study for process liquor in batch mode using flue gas in the mining and mineral processing industry

Carbonation and modeling study for process liquor in batch mode using flue gas in the mining and mineral processing industry

Vanadium Recovery from Bayer Process Liquor Residue

Vanadium Recovery from Bayer Process Liquor Residue

New perspectives for bio-technical treatment of oxalate-containing waste streams from bauxite processing

Alumina is typically produced from bauxite ore using the Bayer process, in which the ore is mixed with alkaline liquor under elevated temperatures. Australian bauxite ore contains a wide range of organics, which detrimentally affect the Bayer process. Therefore, the removal of organic compounds from the alkaline Bayer process liquor is critical in maintaining process efficiency and alumina quality. Oxalate (C2O42−) is a key organic impurity in the Bayer process liquors that requires removal as it increases in concentration in the processing circuit as the Bayer liquor is continually recycled. Compared to conventional physiochemical or physical methods (e.g., chemical precipitation, wet-oxidation, liquor burning), microbial bioreactor treatment processes have the potential to be more economical and environmentally sustainable for oxalate removal. Some Australian alumina refineries have implemented full-scale bioreactors such as moving bed biofilm reactors (MBBRs) and aerobic suspended growth bioreactors (ASGB). While these bioreactors are robust and effective in removing oxalate, they have some limitations, such as the need for pre-acidification of influent and the loss of ammonia (nutrient) through volatilization. Therefore, this study aimed to provide an overview of the fundamentals and recent advances in biotechnical processes for the treatment of alkaline oxalate-containing liquor. Laboratory-scale studies on promising new biotreatment concepts, such as the use of bioelectrochemical systems to facilitate concurrent oxalate degradation and caustics recovery, as well as the utilization of nitrogen-fixing microorganisms to obviate the requirement for external nutrient dosage, are discussed. Perspectives for further research on oxalate-containing waste streams are also proposed.

Ternary extractant system consisting of PC-88A, TOPO, and Versatic 10 for recovery of scandium(III) from nickel laterite processing liquors

Solvent extraction of scandium(III) from an aqueous solution, which simulates a concentrated scandium solution generated from nickel/cobalt mixed-sulfide production process, was performed using a ternary mixed extractant system. Addition of tri-n-octylphosphine oxide and a long-chain alkyl carboxylic acid (Versatic 10) to an organophosphonic ester (PC-88A) drastically improved the separation factor of scandium over zirconium in comparison with that of a single extractant system. The optimum mixing ratio in the ternary extractant system was 10 mol% PC-88A, 60 mol% tri-n-octylphosphine oxide, and 30 mol% Versatic 10. The degree of scandium extraction was 90%, and the separation factors between scandium and other metals (i.e., Al, Fe, Ni, Cr, and Zr) were > 140 at pH 2 with the optimized ternary extractant system. The operating conditions for a countercurrent multistage extraction of scandium were investigated by McCabe–Thiele analysis. Ninety-nine percent recovery from 1800 mg dm−3 scandium was achieved by two- to three-stage countercurrent extraction at the flow ratio (A/O) = 1.01. The stripping efficiency of scandium reached >98% with 7 mol dm−3 H3PO4. Based on the results, a conceptual flowsheet for scandium recovery from waste solutions of laterite ore leachate is proposed.

Carbonate pre-treatment of wood for transformative structural applications through densification

This study investigated carbonate pre-treatment of wood followed by densification for producing advanced wood structural materials. Poplar wood blocks of 100 mm long and 20 mm wide with thickness of 10 mm were treated with sodium carbonate with and without sulfide at different carbonate loadings at 150 ºC for 30 min. Carbonate effectively removed lignin and hemicelluloses which facilitated subsequent wood densification for improving wood mechanical properties . Comparing with wood pre-treatment using sodium hydroxide, carbonate pre-treatment improved wood yield but achieved similar level of wood mechanical strength. Considering sodium carbonate is the key ingredient of commercial pulping process liquors such as spent pulping liquor (black liquor) and green liquor (an aqueous solution of the dissolved inorganic smelt from the combustion of concentrated pulping spent liquor), the present study indicated that low cost, effective, and cleaner wood pre-treatment can be achieved using spent process liquors rather than fresh and expensive sodium hydroxide (white liquor). Laboratory black liquor was used to pretreat the same poplar wood blocks, the good wood mechanical properties of the treated wood after densification confirmed this hypothesis. The practical significance of the present study is the utilization the residue alkali in spent process liquors rather than fresh NaOH for wood pre-treatment to reduce environmental impact. Furthermore, the spent liquor after wood-pretreatment can be directly feed into commercial pulp mill chemical recovery system to reduce capital and operation cost. • Carbonate wood pre-treatment for subsequent wood densification. • Carbonate is effective in delignification and dissolve hemicelluloses. • Pulping spent liquor and green liquor for wood pre-treatment for densification. • Carbonate and pulping liquor pre-treatment improved wood mechanical properties after densification.

Selective sulfate sorption from boric acid factory process liquor: Chitosan-bentonite biocomposite film synthesis as sorbent

Chitosan is a natural polymer that is renewable, biocompatible, and biodegradable. Bentonite is a natural mineral with low environmental effects. For this reason, chitosan- bentonite biocomposite film was synthesized as a sorbent and its characterized by FT-IR, SEM, EDX, CHNS elemental analysis and thermal analysis techniques. The sorbent was utilized for selective sulfate (SO42−) sorption from boric acid factory process liquor, because one of the most important problems in the boric acid production process is sulfate impurity. The sulfate sorption capacity in the acidic region (pH < 5) was determined as 308.38 mg/g and the equilibrium time was determined as 10 min. It has also been found that the sorbent is regenerative and reusable. Sulfate sorption took place by means of primary amine (-NH2) groups in the structure of the biocomposite. In addition, it was considered that the synthesized sorbent acts as a weakly basic anion exchanger resin. It was determined that the total sulfate salt concentration in the process liquor medium decreased by approximately 30.36% depending on the sulfate sorption. In this context, it is considered that the boric acid factory process liquor has been successfully purified.

A generic environmental risk assessment framework for deep-sea tailings placement

Deep-sea tailings placement (DSTP) involves the oceanic discharge of tailings at depth (usually >100 m), with the intent of ultimate deposition of tailings solids on the deep-sea bed (>1000 m), well below the euphotic zone. DSTP discharges consist of a slurry of mine tailings solids (finely crushed rock) and residual process liquor containing low concentrations of metals, metalloids, flotation agents and flocculants. This slurry can potentially affect both pelagic and benthic biota inhabiting coastal waters, the continental slope and the deep-sea bed. Building on a conceptual model of DSTP exposure pathways and receptors, we developed a stressor-driven environmental risk assessment (ERA) framework using causal pathways/causal networks for each of eight pelagic and benthic impact zones. For the risk characterisation, each link in each causal pathway in each zone was scored using four levels of likelihood (not possible, possible, likely and certain) and two levels of consequence (not material, material) to give final risk rankings of low, potential, high or very high risk. Of the 246 individual causal pathways scored, 11 and 18 pathways were considered to be of very high risk and high risk respectively. These were confined to the benthic zones in the mixing zone (continental slope) and the primary and secondary deposition zones. The new risk framework was then tested using a case study of the Batu Hijau copper mine in Indonesia, the largest DSTP operation globally. The major risk of DSTP is smothering of benthic biota, even outside the predicted deposition zones. Timescales for recovery are slow and may lead to different communities than those that existed prior to tailings deposition. We make several recommendations for monitoring programs for existing, proposed and legacy DSTP operations and illustrate how georeferenced causal networks are valuable tools for ERA in DSTP.

Study of Liquor from Hemicelluloses Separation Process in Black Carob Tree Sawdust Biorefinery

This research work utilized pretreated black carob tree sawdust as raw material, given it is plenty of this waste in the Northeast Argentinian region and its objective was to optimize the third stage of a biorefinery process. The acid pretreatment in biorefinery processes was used to extract the maximum quantity of hemicelluloses, to retain the highest cellulose concentration in the pretreated solid and to prevent degradation of sugars contained in the process liquor. Using a central composite design of experiments optimization of hemicellulose extraction of washed partially delignified black carob tree sawdust was achieved. Results from the central composite design of experiments, with two repetitions of central point, have shown that it is possible to obtain liquor yielding 2.9% Solubilized glucose, 54.5% Solubilized xylose, and 0.3% degraded xylose, by an optimal process using 1.5% H2SO4, 7.7% solids for 15.0 min.

Co-production of hydrochar, levulinic acid and value-added chemicals by microwave-assisted hydrothermal carbonization of seaweed

Seaweed is considered a third-generation biomass for transport biofuel production with great potential for bioenergy and biorefinery applications. Microwave-assisted hydrothermal carbonization (HTC) offers a conversion route for seaweed valorization to multiple value-added products. However, the HTC products (such as hydrochar and process liquor) are highly dependent on feedstock properties and HTC conditions. This study investigated the valorization of Laminaria digitata to a range of products (primarily including hydrochar, levulinic acid and 5-hydroxymethylfurfural) through microwave-assisted HTC at a range of low temperatures (160, 180 and 200 °C) and levels of dilute acid addition (1, 2 and 4% H2SO4 concentration). The work suggests an optimized process at a temperature of 200 °C with 4% H2SO4, with levulinic acid and 5-hydroxymethylfurfural in the process liquor achieved the highest yields of 12.5% (12.5 g per 100 g dry L. digitata) and 5.8%, respectively. The obtained hydrochar had a higher heating value of 25.5 MJ/kg volatile solids, comparable to lignite coal. At such a condition the total carbon recovery in the produced hydrochar and process liquor accounted for 84% of carbon in the original seaweed. The 200 °C derived hydrochar presented the highest carbon content of 65.4%, but the lowest abundance in oxygen-containing functional groups compared to the hydrochars obtained under other conditions (160 and 180 °C). The economic benefits of the process might be significantly increased if hydrochar was upgraded into activated carbon instead of being used as a solid fuel.

Two-stage process for the safe utilization of secondary aluminum dross in combination with the Bayer process

Secondary aluminum dross (SAD) is a hazardous waste produced from Al electrolysis, casting, and regeneration. A two-stage process for the safe utilization of SAD was proposed by combining with the Bayer process liquor. In the first stage, approximately 32%, 100%, and 27% of Al, Cl, and F, respectively, from the reactive substances were dissolved into the saturated sodium aluminate solution. A kinetic synergy with a considerable amount of SAD at high temperatures led to an uncontainable reaction, and the frequent addition of SAD at a low dosage was determined for the separation and utilization of H2 and NH3. The inert alumina-bearing compounds and CaF2, which accounted for 50% of the mass of SAD, remained in the residue after the first stage. Efficient conversion of the inert alumina-bearing compounds and elimination of impurities from the Bayer process were both achieved by sintering at 1000 °C for 1 h in the second stage. An alumina extraction efficiency of 99% was obtained at 85 °C after the as-prepared sinter was leached into the saturated sodium aluminate solution. The saturated sodium aluminate solution obtained in the two-stage process was incorporated into the Bayer liquor to produce alumina. Furthermore, cl− and F− were removed by forming sodalite in the desilication process and precipitating CaF2 in the dilute sodium aluminate solution, respectively. Using this novel approach, an estimated 30,000 t/a of SAD has been processed in an alumina refinery in China since 2019. These results provide a novel short process for the safe and efficient utilization of SAD

PHYSICOCHEMICAL PROPERTIES OF SULPHATE WASTE LIQUOR AFTER SOAP EXTRACTION IN THE PRESENCE OF SURFACTANTS

During the wood delignification a multicomponent spent liquor (black liquor) is formed. Depending on the type of wood, black liquor is enriched with valuable extractives. The isolation of extractives from processing liquors and their conversion into biologically active substances, tall products is according to development trend of pulp and paper industry. It includes the introduction of scientific based technologies in manufacturing processes with reference to modern environmental protection requirements. Now the extraction efficiency of sulphate soap does not exceed 75–80% whereby the quality of obtained soap is low. Sulphate soap, especially extracted after hardwood cooking, contains a large amount of impurities. This complicates the process of soap treatment into valuable biologically active substances (beta-sitosterol, etc.). &#x0D; In the present work the addition of demulsifying and coagulating substances into the black liquor is proposed to intensify the hardwood sulphate soap extraction. The chemical colloidal characteristics of the obtained sulphate soap were investigated. Two critical micelle concentration (CMC) were found on the surface tension isotherms. The second critical micelle concentration (CMC2) in the concentration range of 0.9–1.0% CMC2 indicates the restructuring of micelles into a spherocylindrical shape. A comparative qualitative and quantitative analysis of the composition of sulfate soap obtained in industrial conditions and in the presence of selected additives in laboratory was carried out. Surfactants promote the extraction of phytosterol from black liquor obtained from hardwood species cooking. The influence of surfactant addition on the main physical and colloidal chemical characteristics of black liquor before and after isolation of sulphate soap is investigated. A decrease in viscosity and a de foaming of a black liquor solution is observed as a result of the addition of surfactant additives.

Biosorption of Chromium from Spent Semi-Chrome Liquor: Part 1 Effective Pollution Abatement using Bacillus cerus

The current study focuses on the isolation of Bacillus cerus from mangrove rhizosphere and its ability to treat semi-chrome process liquor of upper leathers. This strain has been identified by its molecular characteristics (16s rRNA sequencing) and confirmation has been obtained from neighbor joining tree. Minimum inhibitory concentration of the strain has been found to be 50 ppm. The growth pattern of this organism has been investigated in the presence of chromium, which showed the bacterial strain can grow luxuriantly at 50 and 100 ppm concentration of chromium. Biosorption study has been conducted at different concentrations (50, 100, 150, 200 and 250 ppm) of chromium. The biosorption capability of Bacillus cerus has been found to be 80.78, 73.19, 65.86, 59.44 and 39.27% for 50, 100, 150, 200 and 250 ppm respectively. Chromium sorption from the semi-chrome process liquor by Bacillus cerus has also been investigated, which showed a reduction of 76.15, 68.56, 61.63, 56.29 and 36.51% against 50, 100, 150, 200 and 250 ppm of chromium. Sorption characterization has been carried out by FTIR (Fourier Transform Infra-Red spectroscopy) and SEM (Scanning Electron Microscopy) analyses and the results confirmed the presence of sorption of chromium in Bacillus cerus.

Electrochemical Studies of Structural Materials in Acidic Peroxide Media

Corrosion in paper industries is responsible not only for weakening of metal structures but also for pollution of process liquors and contamination of products. The bleaching sections in pulp and paper industry are among the worst affected by the ravages of corrosion. In bleach plants the materials are exposed to highly corrosive bleaching liquors. Now day’s new norms of safety of environment are forcing paper industries to use peroxide as a bleaching agent instead of chlorine. So in the present study an effort has been done to propose an appropriate material for the construction of future bleach plants keeping in mind their mechanical factors and cost of the material. Accordingly electrochemical polarization tests, E vs. time curve, potentiodynamic polarization curve and cyclic polarization curve were performed on stainless steels samples of 316L, 317L, 2205 and 254SMO in peroxide containing solutions having H2O2, 500 and 1000 parts per million (ppm). The pH of these solutions was kept 4. The Chloride content varied from 0 to 1000 ppm. These tests was performed at room temperature. These tests showed increased resistance against corrosion in order of: 316L<317L<2205<254SMO. Thus 254SMO shows highest resistance for attack of corrosion but keeping in mind fabrication and cost aspects optimal material for treating these peroxide media is recommended to be SS 2205.

Lime properties and dose effects on causticisation of synthetic Bayer liquor

The production of alumina (Al2O3) from bauxite via the Bayer process is underpinned by the use of lime in a variety of process reactions. One of the most important is the causticisation of process liquors, in which lime is used to convert soluble sodium carbonate into caustic, i.e. sodium hydroxide. Causticisation is complicated by unproductive side reactions with sodium aluminate that limit both the extent of causticisation and the efficiency of lime use. Substantial industrial effort and literature has been devoted to optimising causticisation process parameters (e.g. temperature, reaction time, liquor concentrations, and reactor mixing regimes) but little attention has been given to determining the impacts of lime properties and dose. In this study a test procedure was developed and used to evaluate the impact of lime dose, in both slaked and dry quicklime formats, on causticisation performance. This was used to determine the effects of various lime properties, including (1) chemical composition (purity), (2) particle size and (3) reactivity on the causticisation of synthetic Bayer liquors. The results show that, of these parameters, the differences in lime chemical composition had the most significant impact. The methodology can be used to facilitate optimal lime reagent choice and dosage in industrial alumina Bayer refineries. The potential impact of lime utilisation efficiency is also illustrated in the context of overall CO2 emission intensity.

A Rapid Method for Measuring Elastin Degradation and Its Application in Leather Manufacturing

The degradation of elastin in skins during leather manufacturing can increase the yield area, softness and flatness of the leather, but, excessive degradation of elastin in leather processing induces looseness and increases veininess in the final leather product. However, the characterization of the degradation degree of elastin in skins and leathers was mostly studied through histological analysis qualitatively. There is an urgent need to develop a more efficient quantitative analytical strategy to evaluate the degradation of elastin in leather making processes. In this study, a simple and rapid HPLC method is developed for measuring elastin degradation in skins, leathers and leather processing liquors through determining the biological markers of elastin, namely desmosines. The separation of analytes was conducted on an C18 column (4.6 × 150 mm, 4.0 ?m) at 30 ?; the wavelength of diode array detector (DAD) was set at 275 nm; the mobile phases were composed of methanol and aqueous acetic acid (2.0 %, v/v). A gradient elution was carried out at a flow rate of 0.5 mL/min. It has been witnessed that Cr (III) has no effect on the retention time and peak area of desmosines, when the concentration of Cr (III) was in the range of 0 to 200 mg/L. In quantitative analysis, all of the calibration curves showed good linear regression (R2 ? 0.9990) within the tested ranges, and the recovery of desmosines was 100.9 % and 102.6 % for elastin hydrolysate and Cr-tanned elastin hydrolysate, respectively. The content of desmosines in elastin fiber, Cr-tanned elastin fiber and leather manufacturing liquors measured by established HPLC-DAD were comparable to the results obtained by amino acid analyzer. In the wet blue bating process, the quantitative analysis results are consistent with the histological staining results. The results demonstrate that the developed method is accurate and effective and can be readily utilized for the comprehensive process control of leather manufacturing.

Seawater flocculation of clay-based mining tailings: Impact of calcium and magnesium precipitation

In areas where access to water of good quality is limited, the use of seawater in mineral processing can be an option. However, the dewatering of waste tailings is adversely affected, particularly when this follows processing at higher pH. The flocculation response of a synthetic clay-based tailings in seawater to different pH conditions was examined in detail, focusing on conditions promoting precipitation of the divalent cations present. Flocculated aggregate growth and breakage during turbine mixing were monitored in-situ in terms of chord length distributions (by focused beam reflectance measurement) and aggregate image capture, with the resultant hindered settling rates also determined. It was found that flocculation in seawater was substantially impaired at pH values greater than 10.3 due to the precipitation of magnesium species. The addition of the precipitated phase to the synthetic tailings increases both the surface area exposed to flocculant and the number of particles or micro-aggregates then needing further aggregation to attain acceptable settling rates. The direct use of seawater in processing operations without resorting to full desalination does not necessarily have detrimental impacts on tailings flocculation and thickening, provided the operation is conducted at a pH that prevents the precipitation of magnesium present within the process liquors.

Microwave assisted low-temperature hydrothermal treatment of solid anaerobic digestate for optimising hydrochar and energy recovery

With the growth of anaerobic digestion (AD) for biogas production, associated increasing digestate production may cause environmental problems if the increasing agricultural land required for digestate application is limited. An alternative is to valorise the digestate. Microwave assisted low-temperature hydrothermal treatment (MLHT; temperature 100 – 180 °C) was investigated as a post-treatment for AD of grass silage under two scenarios: 1) AD + MLHT and 2) Acid pre-treatment + AD + MLHT. Compared to the original grass silage, the digestates investigated required lower temperatures for carbonization in MLHT owing to their lower cellulose content. The higher MLHT temperatures (160 – 180 °C) led to significant increases in heating value and greater reductions in atomic ratios of O/C and H/C of hydrochar due to dehydration and decarboxylation reactions. As a result, higher temperatures contributed to higher sugar recovery, higher solid solubilization, and better quality of hydrochar. Under the MLHT at 180 °C, the hydrochar produced from digested grass silage in scenario 1 (AD + MLHT) exhibited a mass yield of 0.79 g/g total solid, a carbon content of 63.6% and an ash-free heating value of 27.6 kJ/g volatile solid; the biomethane potential from the process liquor was estimated as 68.7 ml CH4/g total solid. Scenario 1 is preferred over scenario 2 (acid pre-treatment + AD + MLHT) as it gave a higher yield and higher heating value of hydrochar. This study suggests that MLHT is a promising method to 1) produce hydrochar with an energy value comparable to lignite coal, and 2) recover additional biomethane through process liquor recycling.

Extraction of gallium from simulated Bayer process liquor by Kelex 100 dissolved in ionic liquids.

Two 1,2,3-triazolium ionic liquid diluents were evaluated for the extraction of gallium from spent Bayer process liquor by Kelex® 100. The first of these is a hydrophobic ionic liquid with a low water content, which allows the extraction of gallium directly from untreated Bayer process liquor. The second is based on a hydrophilic ionic liquid and which forms an aqueous biphasic system with concentrated salt solutions. The aqueous biphasic system homogenizes upon cooling, which allows homogeneous liquid-liquid extraction of gallium from carbonated Bayer process liquors. The influence of the ionic liquids on the extraction kinetics, mechanism, thermodynamics and selectivity is investigated. Stripping was examined from both systems and their potential for industrialization is discussed. Ionic liquids are shown to beneficially influence the extraction process from thermodynamic and kinetic perspectives. They are therefore promising to solve the issues which have thus far prevented the industrial application of resource-efficient solvent extraction techniques for the recovery of gallium from spent Bayer process liquor.

Radiological assessment of the Bayer process

Naturally occurring radionuclides were studied through the Bayer process by calculating their mass flows. Aluminium of Greece (AoG) provided sample materials and plant data from several process stages. Measurements of radionuclide concentrations were carried out by gamma-ray spectroscopy.The performed measurements show that in the specific case of the AoG plant, the majority of the natural radionuclides were introduced with karst bauxites, which showed higher activity concentrations for nuclides compared to lateritic bauxites. Most of these nuclides accumulated in the bauxite residue, while only a minor portion of uranium isotope 238U was found in alumina, corresponding to 3% of its input value. Uranium was observed to partially dissolve in the process liquors similarly to 40K, whereas the latter was not associated with aluminium hydroxide.All the materials studied in the current research work had radionuclide concentrations well below the exemption limits set by EURATOM Basic Safety Standard, indicating that these naturally occurring radionuclides do not pose a radiological hazard for workers of the AoG plant or the public.

IMPLEMENTASI PENEGAKAN HUKUM TINDAK PIDANA RINGAN (Suatu Diskursus Tindak Pidana Miras Di Polres Jombang)

This study aims to (1) understand, identify and analyze the criminal acts of the law enforcement process liquor in the year 2014 to 2015 in Jombang Police. (2) to understand, identify and analyze the implementation of the law of criminal offenses liquor. (3) to understand, identify and analyze causal criminal offense liquor. This type of research is descriptive research with a qualitative approach seeks to describe or provide an overview of the phenomenon and the events that occurred. The location of this research at the police station and Jombang Jombang.Data collection techniques in this research is observation, interview, and documentation. This data is analyzed by using the method of collection, reduction and verification and presented in the form of descriptive analysis. The conclusion in this study (1) The Regional Regulation No. 16 of 2009 on the supervision and control of liquor in Jombang has been efficient and effective as existing laws regulate the circulation of liquor. (2) Local legislation is able to address the problemsarising from the crime of drinking. With sanctions that still apply 10% (ten percent) of the maximum sanction, it is expected to be free liquor can be added as a reference Jombang zero in offenses liquor.