scholarly journals Hydrometallurgical Process for Zinc Recovery from C.Z.O. Generated by the Steelmaking Industry with Ammonia–Ammonium Chloride Solution

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 83 ◽  
Author(s):  
Shenghai Yang ◽  
Duoqiang Zhao ◽  
Yafei Jie ◽  
Chaobo Tang ◽  
Jing He ◽  
...  
Keyword(s):  
Ammonium Chloride ◽  
Zinc Dust ◽  
Zinc Content ◽  
Agitation Speed ◽  
Purification Process ◽  
Final Solution ◽  
Batch Experiments ◽  
Zinc Extraction ◽  
Zinc Recovery ◽  
Second Stage

In this research, some experimental steps were investigated to recover zinc contained in crude zinc oxide (C.Z.O.). In the first stage, the C.Z.O. was treated in NH3–NH4Cl–H2O solution to dissolve the metals. The optimized leaching conditions in batch experiments were obtained: agitation speed 250 rpm, concentration of ammonia and ammonium chloride 2.5 mol/L and 5 mol/L, respectively, time 30min, temperature 40 °C, and L/S = 6 mL/g. The extraction percentage of zinc was over 81% under the optimized leaching conditions. The kinetic study indicates that zinc extraction from the C.Z.O particles was very rapid. In the second stage, the solution from the leaching process was purified by adding zinc dust to the solution. The Cu, Cd, Pb, Sb, and As could be reduced to levels of 0.03, 0.09, 0.87, 0.22, and 0.12 mg/L after the purification process. Finally, the electrowinning process was used to recover dissolved Zn from the final solution. The zinc content in the electrowon zinc was more than 99.99%.

Direct Measurement of the Hepatointestinal Extraction of Zinc in Cirrhosis and Hepatitis

1981 ◽  
Vol 61 (4) ◽  
pp. 441-444 ◽  
Author(s):  
P. W. N. Keeling ◽  
W. Ruse ◽  
J. Bull ◽  
B. Hannigan ◽  
R. P. H. Thompson
Keyword(s):  
Chronic Hepatitis ◽  
Statistical Significance ◽  
Venous Blood ◽  
Zinc Content ◽  
Atomic Absorption Spectrophotometry ◽  
Zinc Extraction ◽  
Blood Samples ◽  
Peripheral Venous Blood ◽  
Absorption Spectrophotometry ◽  
Biopsy Specimens

1. 65Zn was injected intravenously during transjugular liver biopsy and, from simultaneous hepatic and peripheral venous blood samples, hepatointestinal 65Zn extraction was calculated. Hepatic zinc content was measured in biopsy specimens. 2. On the same occasion samples of liver tissue were taken and their zinc content was measured by atomic absorption spectrophotometry. 3. Seven patients with cirrhosis had significantly lower hepatic zinc content and hepatointestinal zinc extraction than six control patients with mild liver disease. Six patients with chronic hepatitis had a mean hepatointestinal zinc extraction higher than control patients, whereas their mean hepatic zinc content was lower, although the former difference did not achieve statistical significance. 4. These results demonstrate that hepatointestinal extraction of zinc is impaired in cirrhosis, but not in chronic hepatitis.

Upgrading of a co-digestion plant by implementation of a hydrolysis stage

2011 ◽  
Vol 29 (11) ◽  
pp. 1145-1152 ◽  
Author(s):  
Andreas Blank ◽  
Erhard Hoffmann
Keyword(s):  
Retention Time ◽  
Thermal Hydrolysis ◽  
Batch Experiments ◽  
Kitchen Waste ◽  
Primary Sludge ◽  
Biogas Yield ◽  
Bench Scale ◽  
Second Stage ◽  
Hydrolysis Temperature ◽  
Pre Treatment

An existing co-digestion plant needed to be rehabilitated after a 20 year operational period. This was planned to be done in sequence by halving the digester volume for a period of 1.5 years. The aim of the present study was to improve the performance of the halved co-digestion capacity by implementing an upstream thermal hydrolysis reactor or an ultrasonic pre-treatment of the substrates. The results of the ultrasonic bench-scale batch experiments showed that an ultrasonic pre-treatment of the co-substrates ‘municipal bio-waste suspension and excess activated sludge led to disintegration efficiencies of up to 51%. However, treating kitchen-waste and primary sludge in the same manner was not promising as the disintegration yields were rather low. The results of the hydrolysis bench-scale batch experiments showed that the optimal boundary conditions for the hydrolysis reactor were a hydrolysis temperature of about 42 °C at a retention time of 24 h. The results of the continuous two-stage experiments showed that it was possible to reduce the retention time in the second stage to about 24% and to increase the biogas yield to about 12.8 %, and the methane yield to about 28% as a result of the implementation of the hydrolysis reactor in the existing system. After the rehabilitation of the existing digesters it was possible to raise the daily substrate input to the two existing digesters from 312 to 495 m3 day−1 with an upstream hydrolysis reactor volume of only 474 m3.

scholarly journals Co-Digestion of Kitchen Waste with Grass and Leaves after Hyperthermophilic Pretreatment for Methane and Hydrogen Production

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5880
Author(s):  
Przemysław Liczbiński ◽  
Sebastian Borowski
Keyword(s):  
Fatty Acids ◽  
Hydrogen Production ◽  
Organic Material ◽  
Operating Conditions ◽  
Process Performance ◽  
Batch Experiments ◽  
Kitchen Waste ◽  
Biogas Yield ◽  
Second Stage ◽  
Garden Waste

The study investigated co-digestion batch experiments using kitchen waste (KW) and garden waste (GW) collected from individual households. Grass and leaves were first subjected to a 3-day hyperthermophilic pretreatment at 70 °C and 80 °C and then co-digested with kitchen waste at 35 °C and 55 °C. The hyperthermophilic pretreatment resulted in the solubilization of organic material with the release of fatty acids, whereas the biogas yield was negligible. In the second stage, the greatest methane yield of 387 NmL/gVS was achieved for the mono-digestion of leaves, whereas the co-digestion of grass with 50% KW gave the highest hydrogen production of 88 NmL/gVS. Considering the overall process performance, the best operating conditions were established using a 3-day hyperthermophilic pretreatment at 70 °C, followed by co-digestion at 55 °C in the second stage for the mixture of 25% garden waste with 75% KW.

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