scholarly journals Mechanochemical Treatment of Historical Tungsten Tailings: Leaching While Grinding for Tungsten Extraction Using NaOH

2021 ◽  
Vol 13 (6) ◽  
pp. 3258
Author(s):  
Jane Mulenshi ◽  
Saeed Chehreh Chelgani ◽  
Jan Rosenkranz
Keyword(s):  
Treatment Method ◽  
Mechanochemical Treatment ◽  
Low Grade ◽  
Economic Sustainability ◽  
Stirrer Speed ◽  
Critical Factors ◽  
Extraction Techniques ◽  
Digestion Time ◽  
Solid Ratio ◽  
Digestion Mixture

Innovative tungsten (W) extraction techniques are continually being sought because of challenges of low leaching efficiencies, despite using advanced processing units such as autoclaves operating high temperatures and pressures. Compared to conventional leaching, mechanochemical treatment improves the efficiency of leaching. Therefore, in this study, an innovative mechanochemical treatment method, referred to as leaching while grinding (LWG), was employed as a reprocessing option to optimize W recovery from historical tungsten tailings. Experiments were run using the regular two-level factorial design to screen through the four factors of stirrer speed, liquid/solid ratio, temperature, and digestion time to assess their criticality and effects in the LWG process. The stirrer speed and the liquid/solid ratio were the most critical factors in the optimization of W recovery. The maximum W recovery (91.2%) was attained at the highest stirrer speed (410 rpm), low liquid/solid ratio (0.8), long digestion time (6 h), and low leaching temperature (60 °C). The attained low leaching temperature (60 °C) was due to the mechanical activation of scheelite resulting from the simultaneous grinding and leaching. For such low- grade W material, liquid/solid ratio optimizing is critical for maintaining the digestion mixture fluidity, and for environmental and economic sustainability regarding the sodium hydroxide (NaOH) consumption, which was low.

Biocatalytic and chemical leaching of a low-grade nickel laterite ore

2018 ◽  
Vol 115 (3) ◽  
pp. 305 ◽  
Author(s):  
Hasan Ciftci ◽  
Suleyman Atik ◽  
Fatma Gurbuz
Keyword(s):  
Sucrose Concentration ◽  
Low Grade ◽  
Optimum Conditions ◽  
Nickel Laterite ◽  
Chemical Leaching ◽  
Solid Ratio ◽  
Metals Recovery ◽  
Nickel Laterite Ore ◽  
The Difference ◽  
Laterite Ore

Nickel and cobalt recovery from a low-grade nickel laterite ore, supplied from Çaldağ deposit (Manisa, Turkey) were investigated by bio and chemical leaching processes. The fungus, Aspergillus niger was used for biocatalytic leaching experiments. The effects of parameters (solid ratio and sucrose concentration) on the biocatalytic leaching of the ore were initially tested in flasks to obtain the optimum conditions for the A. niger. Then chemical leaching was applied as a comparison to bioleaching, using organic acids (citric, oxalic, acetic and gluconic acids) as well as a mixture of acids. According the results, the maximum dissolution yield of nickel, cobalt and iron were detected respectively as 95.3%, 74.3% and 50.0% by biocatalytic processes which containing 25% (w/v) sucrose and 1% (w/v) solids. The increase in the solid ratio adversely influenced the biocatalytic activity of A. niger. Finally, further tests in reactors (v = 1 and 10 L) were performed using the optimum conditions from the flask tests. The difference in metals recovery between biocatalytic and chemical leaching was significantly important. Bioleaching produced higher Ni and Co extractions (34.3–75.6%) than chemical process.

scholarly journals Endoscopic Mucosal Resection Performed Underwater for Nonampullary Duodenal Epithelial Tumor: Evaluation of Feasibility and Safety

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Goro Shibukawa ◽  
Atsushi Irisawa ◽  
Ai Sato ◽  
Yoko Abe ◽  
Akane Yamabe ◽  
...  
Keyword(s):  
Treatment Method ◽  
En Bloc Resection ◽  
Bloc Resection ◽  
Low Grade ◽  
En Bloc ◽  
Serious Adverse Events ◽  
Epithelial Tumor ◽  
Gastrointestinal Lesions ◽  
Secondary Objective ◽  
Nodular Lesions

Objectives. Recently, opportunities to encounter superficial nonampullary duodenal epithelial tumor (SNADET) have increased. EMR and ESD are performed to treat SNADET. However, the rate of perforation is higher than that of other gastrointestinal lesions, regardless of which method is used. Underwater EMR (UW-EMR) is immersion treatment of SNADET, which has low risk of perforation and can remove lesions safely and completely. In the present study, we retrospectively investigated patients in whom UW-EMR was performed to evaluate the feasibility and safety of UW-EMR for the treatment of SNADET. Methods. The primary endpoint was to evaluate the feasibility of UW-EMR for the treatment of SNADET, and secondary objective was to determine the operation’s safety. Results. There were 14 participants, with a total of 16 lesions, who underwent UW-EMR between August 2015 and December 2017. Histological heteromorphism revealed that seven patients had low-grade adenoma, seven had high-grade adenoma, and two had adenocarcinoma. En bloc resection was performed in 14 lesions. In two patients, nodular lesions were observed in the scar and biopsy confirmed recurrences. There were no serious adverse events including bleeding or perforation. Conclusions. UW-EMR may be a safe and effective treatment method for SNADET, if its therapeutic indication is adequately considered.

Review on New Process and New Reagent of Copper Oxide

2014 ◽  
Vol 1010-1012 ◽  
pp. 1618-1621
Author(s):  
Chi Zhang ◽  
Xiao Dong Jia ◽  
Ya Lin Lu ◽  
Dian Wen Liu ◽  
Xiao Lin Zhang
Keyword(s):  
Research Direction ◽  
Treatment Method ◽  
Low Grade ◽  
Important Research ◽  
Paper Briefly ◽  
Flotation Process ◽  
High Efficient ◽  
New Process ◽  
Copper Ores ◽  
Important Research Direction

The paper briefly analyzes and systematically summarizes flotation process and chemical treatment method of low-grade oxidized copper ores in recent years. The new high-efficient collectors and system of reagent combined usage are developed widely and have become an important research direction of oxidized copper ores.

Hydrometallurgical Treatment of Low Grade Zinc Oxide Ore

2010 ◽  
Vol 158 ◽  
pp. 140-144 ◽  
Author(s):  
Jin Lin Yang ◽  
Shao Jian Ma ◽  
Ping Liu ◽  
Gui Fang Wang ◽  
Xiu Juan Su ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Sulfuric Acid ◽  
Reaction Time ◽  
Sulfuric Acid Concentration ◽  
Low Grade ◽  
Temperature Reaction ◽  
Zinc Extraction ◽  
Solid Ratio ◽  
Hydrometallurgical Treatment ◽  
Influencing Parameters

In this research, a leaching study was carried out to assess the effect of several parameters on zinc extraction in a low grade complex zinc oxide ore in which the grade of Zn is 13 wt.%, and 52.8% of Zn is contained in siderite, 34.63% in limonite and 11.55% in smithsonite. The influencing parameters investigated include sulfuric acid concentration, reaction temperature, reaction time and liquid to solid ratio (L/S). The results show that over 90% of Zn can be extracted from the low grade complex zinc oxide ore when the leaching process is operated in 2M sulfuric acid at 60°C for 2.5h with a liquid to solid ratio of 6:1.

Sulfuric Acid Leaching on Low Grade Oxide Ore

2013 ◽  
Vol 826 ◽  
pp. 122-125 ◽  
Author(s):  
Jin Lin Yang ◽  
Hong Mei Zhang ◽  
Gui Fang Wang ◽  
Shao Jian Ma ◽  
Min Zhang
Keyword(s):  
Sulfuric Acid ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Strong Acid ◽  
Metal Extraction ◽  
Low Grade ◽  
Leaching Rate ◽  
Sulfuric Acid Leaching ◽  
Solid Ratio ◽  
Iron Leaching

In this paper, sulfuric acid leaching was carried out to assess the effect of several parameters on metal extraction in a low grade complex gossan ore in which the grade of zinc and iron is 13% and 40.2%, respectively. Parameters, such as sulfuric acid concentration, liquid to solid ratio and leaching temperature, were studied. The results show that the zinc leaching rate is almost 80%, while the iron leaching rate is about 45% used strong acid with 200g/L. It can be seen from the results that sulfuric acid leaching could not effectively recover zinc from gossan ores studied in this paper because of iron dissolving greatly.

Investigation on the Beneficiation of Low-Grade Manganese Ore in Sichuan

2011 ◽  
Vol 402 ◽  
pp. 518-522 ◽  
Author(s):  
Xiao Mu ◽  
Jian Hua Chen ◽  
Xing Yu Yin
Keyword(s):  
Magnetic Separation ◽  
Sulphuric Acid ◽  
Low Grade ◽  
Manganese Ore ◽  
Optimum Conditions ◽  
Solid Ratio ◽  
Leaching Experiments

Flotation, magnetic separation and leaching experiments have been carried out for the beneficiation of low-grade manganese ore. The results indicated that flotation and magnetic separation could improve the grade of Mn concentrate while the recovery was lower. Better recovery of Mn could be achieved by leaching on optimum conditions, 91.78% of Mn could be recovered by 30 minutes leaching with 25g of sulphuric acid at the liquid/solid ratio of 3:1.

scholarly journals Stent Placement For Intracranial Cysts By Combined Stereotactic/Endoscopic Surgery

2006 ◽  
Vol 59 (suppl_4) ◽  
pp. ONS-474-ONS-480 ◽  
Author(s):  
Ansgar Berlis ◽  
Jan Vesper ◽  
Christoph Ostertag
Keyword(s):  
Stent Placement ◽  
Clinical Symptoms ◽  
Treatment Method ◽  
Low Grade ◽  
Cystic Lesions ◽  
Internal Drainage ◽  
Computed Tomographic ◽  
Stereotactic Frame ◽  
Cyst Aspiration ◽  
New Treatment

Abstract OBJECTIVE: The treatment of space-occupying cystic lesions includes percutaneous cyst aspiration, marsupialization, percutaneous ventriculocystotomy, or Rickham catheter implantation. In some patients, the cysts tend to recur and repeated evacuations are necessary. The authors present a new treatment method with internal drainage of cysts into the ventricular system using a balloon-mounted vascular stent. METHODS: Six patients with cysts of low-grade gliomas, one with monocystic craniopharyngioma, and one with suprasellar arachnoid cyst were treated between September 2003 and May 2005. All patients were symptomatic after multiple previous treatments. Stent implantations were performed under local anesthesia in adults and under general anesthesia in children. In all patients, the stereotactic frame and computed tomographic and magnetic resonance fusion were used for an optimized approach. The treatment was performed in a compassionate manner and the patients were informed about the off-label use of the device. RESULTS: Stent placement was successful in all eight patients without procedure-related complications. Improvement of clinical symptoms was seen in seven out of eight patients. Seven out of eight cysts decreased in size within a follow-up period of up to 23 months (mean, 17 mo; median, 18 mo; range, 6-23 mo). The first patient showed recurrence of the tumor cyst 3 months after initial treatment with a Herkulink stent (5 × 18 mm), followed by retreatment with an Omnilink stent (6 × 28 mm; Guidant Corp., Santa Clara, CA). Stenting was ineffective in one patient. @@CONCLUSION:@@ Treatment of intracranial cystic lesions by internal drainage is possible with the use of stent-assisted ventriculocystostomy.

scholarly journals The Current Status of Treatment Strategies for Cerebral Aneurysms in Nagoya University and Affiliated Hospitals Based on a Questionnaire Survey

2007 ◽  
Vol 13 (1_suppl) ◽  
pp. 39-43
Author(s):  
T. Izumi ◽  
S. Miyachi ◽  
K. Hattori ◽  
H. Iizuka ◽  
Y. Nakane ◽  
...  
Keyword(s):  
Treatment Strategies ◽  
Cerebral Aneurysms ◽  
Treatment Method ◽  
Current Status ◽  
Low Grade ◽  
Anterior Circulation ◽  
International Subarachnoid Aneurysm Trial ◽  
Sedative Drugs ◽  
Almost All ◽  
Anterior Circulation Aneurysms

We investigated differences in the treatment strategies for ruptured aneurysms among 26 hospitals affiliated with Nagoya University and any changes in those strategies based on responses to a questionnaire. We also surveyed the data concerning patients with a ruptured aneurysm collected from our affiliated hospitals between 2001 and 2002. In half of the institutes, angiography is performed immediately after an urgent medical examination, there are only five hospitals (20%) which have a basic policy of terminating the angiography within three to six hours after onset. In half of the institutes, the timing of the treatment also depends on the location of the aneurysm. In particular, the treatment for vertebro-basilar aneurysms tends to be done the next day or later. Low-grade subarachnoid hemorrhage (SAH) patients with mild symptoms tended not to be given any sedative drugs (46%), while patients with SAH in some institutes were sedated without informed consent regardless of the severity. The main treatment method for most anterior circulation aneurysms was clipping. Concerning aneurysms located in the posterior circulation and the origin of the ophthalmic artery, clipping and coiling were equally selected. Almost all the hospitals (92%) responded that their treatment strategy had not changed even after the report of the International Subarachnoid Aneurysm Trial (ISAT). There is a great deal of difference in treatment strategies and indications among institutions. In particular, institutions without neuroendovascular interventionists (NETists) frequently persist in the conventional policy, making it urgently necessary to bring NETists up-to-date on the latest advance in endovascular treatment.

scholarly journals Comparison of perchloroethylene extraction techniques in soil gas survey quantification

2009 ◽  
Vol 7 (3) ◽  
pp. 274-280
Author(s):  
B. Zdravkov ◽  
M. Kubal ◽  
J. Janků
Keyword(s):  
Treatment Method ◽  
Gas Extraction ◽  
Industrialized Countries ◽  
Extraction Techniques ◽  
Volatile Organic ◽  
Survey Results ◽  
Quantitative Results ◽  
Soil Gas Survey ◽  
Vapor Treatment

AbstractSubsurface pollution by volatile organic compounds has emerged as a widespread problem in industrialized countries. This study compares static headspace technique and methanol extraction/purge-and-trap analysis followed by thermal desorption/gas chromatography in attempts for quantification of gas survey results in the determination of these chemicals in soil. Several soils were contaminated with aqueous solution of perchloroethylene (PCE) (140 mg L−1) using a vapor treatment method. Soil spiking took place up to 24 h in desiccator by exposing individual soil samples contained in open 40 mL glass vials to PCE evaporated from the solution. After exposure the samples were stored and analyzed within 2 days. The achieved results strongly suggest that gas extraction can provide quantitative results, regarding PCE concentration in soils, which are not significantly different from liquid based extraction analysis.

Alkaline Leaching of Low Grade Complex Zinc Oxide Ore

2010 ◽  
Vol 158 ◽  
pp. 12-17 ◽  
Author(s):  
Shao Jian Ma ◽  
Jin Lin Yang ◽  
Gui Fang Wang ◽  
Wei Mo ◽  
Xiu Juan Su
Keyword(s):  
Zinc Oxide ◽  
Metal Oxide ◽  
Ammonium Chloride ◽  
Ammonium Carbonate ◽  
Preliminary Investigation ◽  
Low Grade ◽  
Leaching Rate ◽  
Alkaline Leaching ◽  
Solid Ratio ◽  
Zn Content

Alkaline leaching is an important way for treating low grade metal oxide ore, which has some advantages such as low corrosion and low pollution compared to acidic leaching. In order to recover the zinc from a low grade complex zinc oxide ore in which the grade of Zn and Fe are 13 wt.% and 40.2 wt.%, respectively, and 52.8% of Zn is contained in siderite, 34.63% in limonite and 11.55% in smithsonite, this paper presents a preliminary investigation of this type of ore by alkaline leaching method. In this study, ammonia-ammonium chloride and ammonia-ammonium carbonate were used as the leaching reagents. The effects of alkaline concentration, leaching time, leaching temperature and liquid to solid ratio (L/S) were studied, respectively. The results show that 43.15% of initial Zn content was extracted adopting ammonia-ammonium chloride as the leaching reagent in 4.5M at 30°C for 3h with a liquid to solid ratio of 4:1, while 43.07% of Zn recovery was achieved employing ammonia-ammonium carbonate as the leaching reagent at 5M, 30°C and 4:1(L/S). The low leaching rate of Zn is probably attributed to that the zinc contained in siderite was not extracted completely because Zn and Fe exist as isomorphism in siderite.

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