scholarly journals Effect of Quartz on the Preparation of Sodium Stannate from Cassiterite Concentrates by Soda Roasting Process

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 605
Author(s):  
Yuanbo Zhang ◽  
Benlai Han ◽  
Zijian Su ◽  
Xijun Chen ◽  
Manman Lu ◽  
...  
Keyword(s):  
Mole Fraction ◽  
Silicon Content ◽  
Ph Value ◽  
Phase Evolution ◽  
Conversion Ratio ◽  
Roasting Process ◽  
Value Range ◽  
Sodium Stannate ◽  
Roasting Temperature ◽  
Co2 Atmosphere

Sodium stannate (Na2SnO3) has been successfully prepared by a novel process of roasting cassiterite concentrates and sodium carbonate (Na2CO3) under CO–CO2 atmosphere, namely soda roasting-leaching process. However, more than 22 wt. % tin of the cassiterite was not converted into Na2SnO3 and entered the leach residues. Quartz (SiO2) is the predominant gangue in the cassiterite, and phase evolution of SnO2–SiO2–Na2CO3 system roasted under CO–CO2 atmosphere was still uncertain. In this study, the effect of SiO2 in cassiterite concentrates on preparation of Na2SnO3 was clarified. The results indicated that Na8SnSi6O18 was inevitably formed when cassiterite and Na2CO3 were roasted above 775 °C under CO–CO2 atmosphere via the reaction of SnO2 + 6SiO2 + 4Na2CO3 = Na8SnSi6O18 + 4CO2, and formation of Na8SnSi6O18 would be increased with increasing roasting temperature and Si/Sn mole fraction. In addition, it was found that Na8SnSi6O18 was insoluble in the leachate at pH value range of 1–14, which, therefore, was enriched in the leach residues. The silicon content of the cassiterite concentrates should be controlled as lower as possible to obtain a higher conversion ratio of Na2SnO3.

Why is the hydrolytic activity of acetylcholinesterase pH dependent? Kinetic study of acetylcholine and acetylthiocholine hydrolysis catalyzed by acetylcholinesterase from electric eel

2018 ◽  
Vol 73 (9-10) ◽  
pp. 345-351 ◽  
Author(s):  
Alena Komersová ◽  
Markéta Kovářová ◽  
Karel Komers ◽  
Václav Lochař ◽  
Alexander Čegan
Keyword(s):  
Catalytic Activity ◽  
Ionic Strength ◽  
Ph Value ◽  
Hydrolytic Activity ◽  
Initial Substrate ◽  
Electric Eel ◽  
Value Range ◽  
Ph Dependent ◽  
Ph Range ◽  
Initial Substrate Concentration

AbstractThe dependence of the activity of acetylcholinesterase from electric eel at a pH value range of 4.8–9.8 (phosphate buffer), regarding acetylcholine and acetylthiocholine hydrolysis, was determined at 25 °C, ionic strength of 0.11 M, and initial substrate concentration of 4 mM. At a pH range of 4.8–9.8, the dependencesA(pH) form a sigmoid increasing curve with the maximum catalytic activity at a pH range 8–9.5. For acetylcholine hydrolysis, the kinetic reason for such an increase inAconsists mainly of an increase in the rate constantk2(Michaelis-Menten) model with increasing pH of the reaction mixture. For acetylthiocholine hydrolysis, the kinetic explication of the determined dependenceA(pH) is more complicated.

scholarly journals Effects of sodium roasting on the leaching rate of boron-bearing tailings and its mechanism analysis

2018 ◽  
Vol 5 (8) ◽  
pp. 172342
Author(s):  
Chengxi Zou ◽  
Zhenyu Tang ◽  
Wei Xie ◽  
Hanguang Fu ◽  
Jiacai Kuang ◽  
...  
Keyword(s):  
Scientific Basis ◽  
Raw Material ◽  
Sodium Borate ◽  
Mechanism Analysis ◽  
Leaching Rate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Roasting Process ◽  
Roasting Temperature ◽  
Theoretical Amount

The study reported was intended to improve the leaching rate of boron-bearing tailings, using a method of sodium roasting that uses boron-bearing tailings as the raw material and Na 2 CO 3 as the sodium agent. The effects of the roasting temperature and Na 2 CO 3 amount on the leaching rate of boron-bearing tailings are mainly evaluated. The morphology and composition of the samples after sodium roasting are analysed by scanning electron microscopy and X-ray diffraction. The results show that sodium roasting can significantly improve the leaching rate of boron-bearing tailings. Under the optimal conditions where roasting temperature is 950°C, Na 2 CO 3 amount is five times the theoretical amount and roasting time is 2 h, the leaching rate of boron-bearing tailings is up to 86.78%. Based on the analysis of the characterization results and the mechanism analysis of the sodium roasting process, the main reason for the increase of leaching rate is the reaction between Na 2 O produced by the decomposition of Na 2 CO 3 and the boron in boron-bearing tailings resulting in soluble sodium borate. The results provide a scientific basis for the efficient comprehensive use of boron-bearing tailings.

Gaseous Fluorides Formation Mechanism in the Roasting Process of the Fluorite-Bearing Iron Concentrate

2013 ◽  
Vol 690-693 ◽  
pp. 3498-3505 ◽  
Author(s):  
Yi Ci Wang ◽  
Jian Liang Zhang ◽  
Jing Wang ◽  
Fang Zhang ◽  
Guo Ping Luo
Keyword(s):  
Thermal Analysis ◽  
Water Vapor ◽  
Formation Mechanism ◽  
Theoretical Basis ◽  
Emission Rate ◽  
Sintering Process ◽  
Iron Concentrate ◽  
Roasting Process ◽  
Fluorine Emission ◽  
Roasting Temperature

The gaseous fluorides formation mechanism in the roasting process of the fluorite-bearing iron concentrate was studied by thermodynamic calculation, differential thermal analysis (DTA) and chemical analysis. The results show that fluorine in the fluorite-bearing iron concentrate begins to escape since 400~500°C, and the emission rate of fluorine significantly increases when the temperature is above 1100°C; in the roasting process of fluorite-bearing iron concentrate, SiO2, K2O, Na2O, MgO, Al2O3 in the gangue and water vapor in roasting atmospher react with CaF2 in fluorite to generate such gaseous fluorides as SiF4, KF, NaF, MgF2, AlF3 and HF; with the increase of roasting temperature, the emission rate of fluorine increases obviously; and the water vapor in roasting atmosphere can improve escaping of fluorine.The results provide a theoretical basis for the improvement of roasting technology to reduce fluorine emission in the roasting or sintering process of Baiyanobo iron concentrate.

Function mechanism of CO-CO2 atmosphere on the formation of Na2SnO3 from SnO2 and Na2CO3 during the roasting process

2016 ◽  
Vol 301 ◽  
pp. 102-109 ◽  
Author(s):  
Bingbing Liu ◽  
Yuanbo Zhang ◽  
Zijian Su ◽  
Guanghui Li ◽  
Tao Jiang
Keyword(s):  
Function Mechanism ◽  
Roasting Process ◽  
Co2 Atmosphere

Study on Process of Microwave Magnetizing Roast for Low-Grade Hematite

2011 ◽  
Vol 201-203 ◽  
pp. 1816-1820
Author(s):  
Jie Li ◽  
Bao Wei Li ◽  
Bang Wen Zhang ◽  
Lei Wang
Keyword(s):  
Carbon Content ◽  
Magnetic Separation ◽  
Low Grade ◽  
Percent Reduction ◽  
Iron Smelting ◽  
Magnetic Process ◽  
P Content ◽  
Roasting Process ◽  
Roasting Temperature ◽  
Roasting Time

The microwave magnetic roasting process of low-grade hematite under low temperature was studied experimentally. The effects of roasting temperature, carbon content and roasting time on the reduction and magnetic separation were investigated. It shows that the best percent reduction is 10.96％(near to theoretical value 11.11%)which can be obtained under the condition of roasting temperature of 650°С , carbon content of 1.0% and roasting time of 10 minute. The results of magnetic separation show that the best magnetic separation grade for the sintered ore occurs at 570 instead of 650°С owing to the sintering of ore powders at high temperature of 650°С . Further ball-milling and magnetic separation of this concentrate produces two kind of final concentrate, one of which is in grade 65.6% with the recovery being 45.3%, and the other is in grade 63.4% with the recovery being 62.6％. After the magnetic separation, concentrate ore meets the iron-smelting requirements because of its low S and P content and high grade. This magnetic process results in the enrichment of RE and Nb in tailing ore, which can be reused for the extraction of Rare Earth and Nb.

Effective Extraction of Vanadium and Chromium from High Chromium Content Vanadium Slag by Sodium Roasting and Water Leaching

2016 ◽  
Vol 863 ◽  
pp. 144-148 ◽  
Author(s):  
Ming Li ◽  
Liang Xiao ◽  
Jing Jing Liu ◽  
Zhi Xin Shi ◽  
Zi Bi Fu ◽  
...  
Keyword(s):  
Chromium Content ◽  
Leaching Rate ◽  
Vanadium Slag ◽  
Water Leaching ◽  
Sodium Salts ◽  
High Chromium ◽  
Effective Factor ◽  
Roasting Process ◽  
Roasting Temperature ◽  
Roasting Time

The extraction of vanadium and chromium from high chromium content vanadium slag by salt roasting and water leaching process has been investigated, which uses mixed sodium salts (Na2CO3 and NaOH) as additive agent in roasting process. The mineralogical morphology was prospected by TG-DSC, XRD, SEM and EDS. The oxidation of slag and transversion of V/Cr-containing phase and sodium salts have been discussed. It has been demonstrated that the presence of NaOH contributes to decompose spinel and olivine phases, which is beneficial to reduce the roasting temperature and elevate V, Cr leaching ratio. The roasting parameters have been studied as a function of roasting temperature, roasting time and ratio of alkali, in which the roasting temperature is the most effective factor on the leaching rate of vanadium and chromium. Under the optimum condition, the leaching rates of V and Cr reached 95.8% and 97.6%, respectively.

Comparison of Different Ion-Exchangers’ Performances for Removal of Cadmium(ll) from Aqueous Solution

2012 ◽  
Vol 550-553 ◽  
pp. 2205-2209
Author(s):  
Chun Bo Liang ◽  
Ming Yu Li ◽  
Qing Xuan Zeng
Keyword(s):  
Aqueous Solution ◽  
Ion Exchange ◽  
Ph Value ◽  
Ion Exchange Resins ◽  
Carboxylate Groups ◽  
Cation Exchangers ◽  
Value Range ◽  
Exchange Resins ◽  
Ion Exchange Fiber ◽  
Cationic Exchanger

In this paper, comparison of the ion-exchange characteristics of removal cadmium (Ⅱ) ions from aqueous solution was investigated. In the experiments, three strong cation-exchangers, 732 resin, K-1 fiber and ZB-1 fiber with sulfonate groups, weak cationic exchanger 724 resin with carboxylate groups and X-1 chelating fiber with diethylamino functional groups as well as the AK-22 amphoteric fiber with amino and carboxylate groups were used. In the pH value range from 2.0 to 7.0, all the candidate materials had the maximal removal Cd (Ⅱ) up to 98% except AK-22 (only 65%). The loading and eluting kinetics results showed that the exchange rate of ion-exchange fibers (especially ZB-1) were higher than ion-exchange resins. Therefore, it was found that ZB-1 ion-exchange fiber was the most effective for removal and elution of Cd (Ⅱ) and had the potential application for the purification of waters polluted by Cd (Ⅱ).

Study on the Toxicity of Cyanogen-Containing Industrial Waste Residues

2010 ◽  
Vol 160-162 ◽  
pp. 927-932
Author(s):  
Jin Liu ◽  
Bin Quan Jiao ◽  
Dong Wei Li
Keyword(s):  
Standard Deviation ◽  
Acute Toxicity ◽  
Industrial Waste ◽  
Ph Value ◽  
Variation Coefficient ◽  
Acute Toxicity Test ◽  
Current Analysis ◽  
Leaching Toxicity ◽  
Value Range ◽  
The Mean

By using a series of tests for corrosivity, acute toxicity and leaching toxicity of cyanide-containing wasteresidues, the toxicity of cyanide-containing wasteresidues has been investigated. According to acute toxicity test, the wasteresidues showed no acute toxicity. The experiment further indicated that the cyanide compounds were tested in the 0.15 ～ 0.60 concentration rang, mean (0.429), standard deviation (0.195) and variation coefficient (45.5%). The pH value range for leaching liquor of slag yard was 9.21～13.09 at the mean 10864, and the standard deviation and variation coefficient were 1.553 and 14.3% respectively. The research revealed that the cyanide compounds content in wasteresidue samples was distributed very unevenly, and the content of cyanide compounds was not exceeded the standard. Based on the current analysis results, those cyanide-containing wasteresidues were defined as hazardous solidwastes with corrosivity.

scholarly journals Effects of Different Fermented Feeds on Production Performance, Cecal Microorganisms, and Intestinal Immunity of Laying Hens

Animals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2799
Author(s):  
Lijuan Guo ◽  
Jing Lv ◽  
Yinglu Liu ◽  
Hui Ma ◽  
Bingxu Chen ◽  
...  
Keyword(s):  
Laying Hens ◽  
Ph Value ◽  
Basal Diet ◽  
Conversion Ratio ◽  
Feed Conversion Ratio ◽  
Production Performance ◽  
Intestinal Immunity ◽  
Feed Conversion ◽  
Fermented Feed ◽  
Cecal Microflora

This experiment was conducted to investigate the effects of different compound probiotics on the performance, cecal microflora, and intestinal immunity of laying hens. A total of 270 Jing Fen No.6 (22-week-old) were randomly divided into 3 groups: basal diet (CON); basal diet supplemented with 6% fermented feed A by Bacillussubtilis,Lactobacillus, and Yeast (FA); and with 6% fermented feed B by C. butyricum and L. salivarius (FB). Phytic acid, trypsin inhibitor, β-glucan concentrations, and pH value in fermented feed were lower than the CON group (p < 0.05). The feed conversion ratio (FCR) in the experimental groups was decreased, while albumen height and Haugh unit were increased, compared with the CON group (p < 0.05). Fermented feed could upregulate the expression of the signal pathway (TLR4/MyD88/NF-κB) to inhibit mRNA expression of pro-inflammatory cytokines (p < 0.05). Fermented feed promoted the level of Romboutsia (in the FA group) Butyricicoccus (in the FB group), and other beneficial bacteria, and reduced opportunistic pathogens, such as Enterocooccus (p < 0.05). Spearman’s correlations showed that the above bacteria were closely related to albumen height and intestinal immunity. In summary, fermented feed can decrease the feed conversion ratio, and improve the performance and intestinal immunity of laying hens, which may be related to the improvement of the cecal microflora structure.

scholarly journals Temperature coverage simulation of horizontal cylinder type coffee roasting machine

2021 ◽  
Vol 922 (1) ◽  
pp. 012031
Author(s):  
F Fachruddin ◽  
S Syafriandi ◽  
R Fadhil
Keyword(s):  
Bulk Density ◽  
Horizontal Cylinder ◽  
Roasted Coffee ◽  
Actual Temperature ◽  
Coffee Beans ◽  
Roasting Process ◽  
Study Results ◽  
Roasting Temperature ◽  
Roasted Coffee Beans ◽  
Coffee Roasting

Abstract This study aims to simulate the temperature distribution of coffee roasting machines and study the profile of coffee beans roasted using a horizontal cylinder-type roaster. The coffee used in this study is arabica. The simulation method for the temperature estimation in the coffee roasting process uses the Solidworks Flow Simulation 2016 software, while the actual temperature measurement using a thermocouple is simulated with the Surfer software version 16. Furthermore, each stage of the coffee roasting process has been carried out, including the weight of the material, the roasting temperature, and the bulk density. The final step is to observe the profile of the roasted coffee beans at every minute of treatment. The study results indicate a difference between the approximate temperature simulation (top 176.85°C, bottom 191.97°C) and the actual temperature measured results (upper 214°C, bottom 220°C). The weight of the material (coffee green bean), the roasting temperature, and the bulk density during the test experienced regular movements from the beginning to the end of the treatment. The profile of roasted coffee beans shows a darker color movement along with the longer roasting time used. The profile of the roasted coffee beans will be beneficial in determining at which level of roasting you want (light, medium, medium-dark, dark).

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