A Review of Thiocyanate Hydrometallurgy for the Recovery of Gold

Over the past century, numbers of hydrometallurgical processing technologies have been conducted for gold leaching in mining and second resource, such as cyanidation, being with high toxicity and low reaction rate, and non-cyanide---thiosulphate leaching and thiourea leaching, etc, having relatively high reagent consumption. Recently, ammonium thiocyanate was selected as leaching reagent in the laboratory study. Just as some papers shown, thiocyanate can be complexed tightly with Au+ or Au3+ to form water-soluble complexes according to the dynamic and thermodynamic system of thiocyanate gold and regenerated or obtained as a by-product in technological processes. And the extraction process is affected by many factors, such as thiocyanate concentration, oxidant concentration, liquid-solid ratio, temperature, and reaction time, especially pH and the category of oxidants, which can be chosen properly to make the method extensively applied in industrialization. Recent studies have shown that the gold leaching with thiocyanate under alkaline conditions is also viable using oxygen as oxidant. Then this article compares and analyzes the use of different oxidants in acid or alkali environment reaching a 96% leaching efficiency and the techniques of gold recycle from thiocyanate gold solutions. However, as the restriction for post-processing cost of thiocyanate and the strict requirement for the equipment in the acidic conditions or high pressure conditions, additional research should be directed towards making incorporation with other extraction methods perfectly. Two development tendencies are presented in this paper: (1) as additive; (2) as the lixiviant under alkaline or neutral conditions.

Download Full-text

THE EXTRACTION OF BROWN ALGAE (Sargassum sp) THROUGH CALCIUM PATH TO PRODUCE SODIUM ALGINATE

Jurnal Bahan Alam Terbarukan ◽

10.15294/jbat.v7i1.11412 ◽

2018 ◽

Vol 7 (1) ◽

pp. 64-69

Author(s):

Octovianus S. R. Pasanda ◽

Abdul Azis

Keyword(s):

Water Content ◽

Brown Algae ◽

Linear Chain ◽

Dry Weight ◽

Extraction Process ◽

Extraction Methods ◽

Ash Content ◽

Water Soluble ◽

Raw Material ◽

Total Dry Weight

Brown algae is a source of sodium alginat raw material. One type of brown algae that is found to grow in Indonesian waters is Sargassum echinocarphum. Brown algae including one type of seaweed that grows in many waters of Indonesia, especially the waters of Eastern Indonesia. Alginat is a pure polysaccharide of uronic acid contained in a brown algae cell wall arranged in the form of long linear chain alginic acids with levels reaching 40% of the total dry weight. The alginat form in general is sodium alginat, a water soluble alginat salt. The purpose of this research is to know the quality of alginat include alginat rendamen, water content, ash content, and viscosity. Conventional extraction methods from brown algae into sodium alginat produces the highest yield percentage of 32.42%, resulting from the extraction for 7 hours at 60 C. The lowest average yield percentage resulted in 5 hours extraction process of 2.78%, the average water content of 20.37 - 23.30%, the mean ash content of 22.28 - 34.87%, and the viscosity ranged between 18, 0 - 19.8 Cp.

Download Full-text

Structure and Bioactivities of Porphyrans and Oligoporphyrans

Current Pharmaceutical Design ◽

10.2174/1381612825666190430111725 ◽

2019 ◽

Vol 25 (11) ◽

pp. 1163-1171 ◽

Cited By ~ 2

Author(s):

Lihua Geng ◽

Jing Wang ◽

Zhongshan Zhang ◽

Yang Yue ◽

Quanbin Zhang

Keyword(s):

Drug Delivery ◽

Therapeutic Potential ◽

Biological Activities ◽

Great Influence ◽

Physical Method ◽

Extraction Process ◽

Extraction Methods ◽

Sulfated Polysaccharide ◽

Water Soluble ◽

Hot Water

Background: Pyropia (Porphyra), commonly known as nori or laver, is an important food source in many parts of the world. Edible dried Pyropia contains numerous nutrients and biofunctional components, including proteins, vitamins, eicosapentaenoic acid, minerals, carotenoids, mycosporine-like amino acids, and carbohydrate, and one of the compounds which we are interested in is porphyran, a sulfated polysaccharide comprising the hot-water-soluble portion of Pyropia cell walls. Researchers have performed a large number of in-depth studies on the biological activity and potential therapeutic applications of porphyrans and oligoporphyrans. Methods: This mini review aims to provide comprehensive and update overview on the source, extraction, structure, biological activities and structure-activity relationships of porphyrans and oligoporphyrans based on the studies in the past 30 years which were included in Web of Science. Results: The structure of porphyran has been basically determined given that its straight chain is relatively simple, and the skeleton structure has been described. The extraction methods were simplified continuously, but different extraction methods and post- processing methods still had great influence on the structure and composition of porphyran, so there was no standardized extraction process which can achieve quality control until now. In order to obtain oligoporphyrans, there are a variety of degradation methods, including chemical method, physical method and enzymatic method, but it is worth mentioning that specific degradation enzyme is still unavailable. Studies on the biological and pharmacology properties include antioxidant, anti-tumor, anti-inflammatory, immunomodulation, anti-cardiovascular and cerebrovascular diseases and drug delivery. Conclusion: Owing to the therapeutic potential and drug delivery applications, porphyran and oligoporphyrans are expected to be further developed as a medicine against human diseases, as well as a supplement in cosmetics and health products.

Download Full-text

Improved understanding of Sodium hydroxide concentration role and kinetic model of cryolite reactive extraction in cathode Spent Pot Linings

Polish Journal of Chemical Technology ◽

10.2478/pjct-2021-0006 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Blaž Tropenauer ◽

Dušan Klinar ◽

Janvit Golob

Keyword(s):

Kinetic Model ◽

Film Theory ◽

Critical Role ◽

Extraction Process ◽

Water Soluble ◽

Reactive Extraction ◽

Smelting Process ◽

Solid Ratio ◽

Whole Process ◽

Internal Particle

Abstract Spent Pot Lining (SPL) cathode pot, waste from the aluminium smelting process needs detoxification from cyanides, washing out water-soluble salts and extraction of the cryolite (Na3AlF6) decomposition products to be recycled. Revealed cryolite decomposition mechanism with NaOH opens possibilities to explore its critical role in the reactive extraction process. Common Na+ ion from NaOH hinders the solubility of the product but also drives mass transfer to the reaction site. Reaction mass balance provides adequate liquid to solid ratio (L/S) and NaOH concentration range. A newly developed kinetic model based on Whitman film theory and NaOH mass flow enables prediction of the reaction time to decompose cryolite to a low enough level. Results show that the internal particle resistance to transport (1/ks) is 19 times larger than the external (1/kl) one and governs the whole process.

Download Full-text

Increasing Yield and Antioxidative Performance of Litchi Pericarp Procyanidins in Baked Food by Ultrasound-Assisted Extraction Coupled with Enzymatic Treatment

Molecules ◽

10.3390/molecules23092089 ◽

2018 ◽

Vol 23 (9) ◽

pp. 2089 ◽

Cited By ~ 6

Author(s):

Shuyi Li ◽

Yanjie Yang ◽

Junsheng Li ◽

Zhenzhou Zhu ◽

Jose Lorenzo ◽

...

Keyword(s):

Extraction Process ◽

Extraction Methods ◽

Enzyme Concentration ◽

Ultrasonic Power ◽

Ultrasound Assisted Extraction ◽

Solid Ratio ◽

Assisted Extraction ◽

Ultrasonic Time ◽

Functional Components ◽

Litchi Pericarp

Extraction with organic solvents is a traditional method to isolate bioactive compounds, which is energy-wasting and time-consuming. Therefore, enzyme and ultrasound treatments were combined to assist the extraction of oligomeric procyanidins from litchi pericarp (LPOPC), as an innovative approach to replace conventional extraction methods. Under optimum conditions (enzyme concentration 0.12 mg/mL, ultrasonic power 300 W, ultrasonic time 80 min, and liquid/solid ratio 10 mL/g), the yield of LPOPC could be improved up to 13.5%. HPLC analysis indicated that the oligomeric procyanidins (OPC) content of LPOPC from proposed extraction was up to 89.6%, mainly including (−)-epicatechin, procyanidin A1, A2, and A-type procyanidin trimer. Moreover, LPOPC powder was added in baked food to inhibit the lipid peroxidation. It was found that 0.2% (w/w) of LPOPC could maintain the quality of cookies in the first 7 days, by decreasing the peroxide values. The procyanidin dimers and trimers in LPOPC played more important roles as antioxidants compared to monomers during storage. The results also showed that the combined extraction process can be considered as a useful and efficient method for the extraction of functional components from other plant sources.

Download Full-text

Experiment Study on Ultrahigh Pressure Extraction of Protein Components from Sika Deer Pilose Antler

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.550-553.1841 ◽

2012 ◽

Vol 550-553 ◽

pp. 1841-1844 ◽

Cited By ~ 1

Author(s):

Wen Jing Guo ◽

Guo Jun Yang ◽

Yong Ren Chen ◽

Shou Qin Zhang

Keyword(s):

Room Temperature ◽

Sika Deer ◽

Extraction Process ◽

Extraction Methods ◽

Extraction Time ◽

Ultrahigh Pressure ◽

Experimental Conditions ◽

Solid Ratio ◽

Pressure Extraction ◽

Protein Components

An Ultrahigh pressure extraction technique (UPET) is presented for the extraction of protein components from sika deer pilose antler. Various experimental conditions of the UPET process, such as extraction pressure (50-300 MPa), extraction time (0-10 min) and liquid/solid ratio (2-10 mL•g−1), were investigated to optimize the extraction process. The content of protein components in pilose antler extract by UPET for 4 min was higher than those using ultrasonic extraction (UE) for 30 min, heat reflux extraction (RE) for 12 h and soaking extraction (SE) at room temperature for 24 h respectively. From the viewpoints of extraction time, the proteins content in pilose antler extract and energy consumption in the extraction process, UPET was more effective than the conventional extraction methods studied.

Download Full-text

Extraction of Mogroside and Limonin with Different Extraction Methods and its Modeling

International Journal of Food Engineering ◽

10.1515/1556-3758.2361 ◽

2012 ◽

Vol 8 (2) ◽

Cited By ~ 5

Author(s):

Jing Liu ◽

Can Liu ◽

Yonghai Rong ◽

Long Rong

Keyword(s):

Thin Film ◽

Natural Products ◽

Mass Production ◽

Extraction Process ◽

Extraction Methods ◽

Ultrasonic Extraction ◽

Citrus Reticulata ◽

Comparison Of Methods ◽

Economical Method ◽

Siraitia Grosvenorii

The extraction yields of mogroside from Siraitia grosvenorii fruits and limonin from orange (Citrus reticulata Blanco) seeds were compared with different extraction methods, respectively. Maceration extraction, stirring extraction, ultrasonic extraction and flash extraction were used for the extraction. The extraction process was modeled using the concept of thin film which provides the resistance to transfer. The results showed that the maximum yields of mogroside (4.11%) and limonin (0.65%) were obtained by ultrasonic extraction and flash extraction respectively. Owing to its shorter extraction time, flash extraction would be an economical method for the mass production of triterpenes from natural products. The model was found to be fit for the comparison of methods for the extraction and provided good correlation of the data. The model could be mainly used in the practical extraction process.

Download Full-text

Phycocyanin content and nutritional profile of Arthrospira platensis from Mexico: efficient extraction process and stability evaluation of phycocyanin

BMC Chemistry ◽

10.1186/s13065-021-00746-1 ◽

2021 ◽

Vol 15 (1) ◽

Author(s):

Sanghamitra Khandual ◽

Edgar Omar Lopez Sanchez ◽

Hugo Espinosa Andrews ◽

Jose Daniel Padilla de la Rosa

Keyword(s):

Storage Temperature ◽

Extraction Process ◽

Arthrospira Platensis ◽

Extraction Methods ◽

Precipitation Method ◽

Partial Purification ◽

Natural Food ◽

Solvent Ratio ◽

C Storage ◽

Dry Biomass

AbstractPhycocyanin is a blue natural food colorant with multiple health benefits. Here we propose an efficient phycocyanin extraction method from Arthrospira platensis from Mexico. Three extraction methods were applied to optimize the extraction process, using water and buffer as solvents, with three pH values at two agitation times. The highest phycocyanin, 54.65 mg/g, was extracted from dry biomass with water as a solvent using an ultrasonication bar. The optimum condition of extraction was determined to be 1:50 biomass/solvent ratio for dry biomass, with the freeze/thaw method for 20 min repeated twice, and then agitated at 120 rpm for 24 h. The phycocyanin content was 48.88 mg/g biomass, with a purity of 0.47. For scalable phycocyanin productivity, the sonication method is recommended as there is no statistical difference. The phycocyanin stability was best at − 20 °C storage temperature at pH 7 for 35 days. Partial purification with ammonium sulfate was found to be suitable as a fractional precipitation method, first at 0–20% and then 20–65%, to get purity nearly 1. Total protein was found to be 55.52%, and total amino acids after phycocyanin extraction was 33%. The maximum phycocyanin yield using water as a solvent was the most interesting result regardless of the method used for extraction.

Download Full-text

Facile fractionation of bamboo hydrolysate and characterization of isolated lignin and lignin-carbohydrate complexes

Holzforschung ◽

10.1515/hf-2020-0040 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Xiaodi Wang ◽

Yongchao Zhang ◽

Luyao Wang ◽

Xiaoju Wang ◽

Qingxi Hou ◽

...

Keyword(s):

Solvent Extraction ◽

Organic Solvent ◽

Extraction Process ◽

Water Soluble ◽

Organic Solvent Extraction ◽

Glycoside Linkage ◽

Potential Applications ◽

Tremendous Amount ◽

Main Components ◽

Hemicellulosic Sugars

AbstractAn efficient separation technology for hydrolysates towards a full valorization of bamboo is still a tough challenge, especially regarding the lignin and lignin-carbohydrate complexes (LCCs). The present study aimed to develop a facile approach using organic solvent extraction for efficiently fractionating the main components of bamboo hydrolysates. The high-purity lignin with only a trace of carbohydrates was first obtained by precipitation of the bamboo hydrolysate. The water-soluble lignin (WSL) fraction was extracted in organic solvent through a three-stage organic solvent extraction process, and the hemicellulosic sugars with increased purity were also collected. Furthermore, a thorough characterization including various NMR techniques (31P, 13C, and 2D-HSQC), GPC, and GC-MS was conducted to the obtained lignin-rich-fractions. It was found that the WSL fraction contained abundant functional groups and tremendous amount of LCC structures. As compared to native LCC of bamboo, the WSL fraction exhibited more typical LCC linkages, i.e. phenyl glycoside linkage, which is the main type of chemical linkage between lignin and carbohydrate in both LCC samples. The results demonstrate that organic phase extraction is a highly efficient protocol for the fractionation of hydrolysate and the isolation of LCC-rich streams possessing great potential applications.

Download Full-text

Integrated Metabolomics and Transcriptomics Using an Optimised Dual Extraction Process to Study Human Brain Cancer Cells and Tissues

Metabolites ◽

10.3390/metabo11040240 ◽

2021 ◽

Vol 11 (4) ◽

pp. 240

Author(s):

Alison Woodward ◽

Alina Pandele ◽

Salah Abdelrazig ◽

Catherine A. Ortori ◽

Iqbal Khan ◽

...

Keyword(s):

Metabolic Pathways ◽

Extraction Method ◽

Limit Of Detection ◽

Rna Extraction ◽

Extraction Process ◽

Extraction Methods ◽

Serum Starvation ◽

Extraction Techniques ◽

Metabolic Genes ◽

Dual Extraction

The integration of untargeted metabolomics and transcriptomics from the same population of cells or tissue enhances the confidence in the identified metabolic pathways and understanding of the enzyme–metabolite relationship. Here, we optimised a simultaneous extraction method of metabolites/lipids and RNA from ependymoma cells (BXD-1425). Relative to established RNA (mirVana kit) or metabolite (sequential solvent addition and shaking) single extraction methods, four dual-extraction techniques were evaluated and compared (methanol:water:chloroform ratios): cryomill/mirVana (1:1:2); cryomill-wash/Econospin (5:1:2); rotation/phenol-chloroform (9:10:1); Sequential/mirVana (1:1:3). All methods extracted the same metabolites, yet rotation/phenol-chloroform did not extract lipids. Cryomill/mirVana and sequential/mirVana recovered the highest amounts of RNA, at 70 and 68% of that recovered with mirVana kit alone. sequential/mirVana, involving RNA extraction from the interphase of our established sequential solvent addition and shaking metabolomics-lipidomics extraction method, was the most efficient approach overall. Sequential/mirVana was applied to study a) the biological effect caused by acute serum starvation in BXD-1425 cells and b) primary ependymoma tumour tissue. We found (a) 64 differentially abundant metabolites and 28 differentially expressed metabolic genes, discovering four gene-metabolite interactions, and (b) all metabolites and 62% lipids were above the limit of detection, and RNA yield was sufficient for transcriptomics, in just 10 mg of tissue.

Download Full-text