Zinc Oxide Fume Research Articles

Experimental Study on Arsenic Removal from Leaching Solution of Zinc Oxide Fume

Experimental Study on Arsenic Removal from Leaching Solution of Zinc Oxide Fume

Health hazards resulting from exposure to zinc and its inorganic compounds in industry

This article deals with health risks resulting from exposure to zinc and its inorganic compounds in industry. The main source of zinc exposure are fumes generated during thermal and chemical processes, mainly zinc oxide fume formed by immediate oxidation of metallic zinc vapor formed during high-temperature processes, as well as dust generated during the mechanical processing of zinc-containing materials. It is recognized that zinc ions are responsible for health effects of exposure to dust/fumes of the majority of zinc compounds, and the final effect of exposure depends on the degree of dispersion of dusts/fumes suspended in the air. Since the effects of exposure depends on the particle size, occupational exposure limits have began to be established separately for respirable and inhalable fractions. A critical effect of acute exposure to respirable fraction is a "fume fever" which in chronic exposure occurs as an effect associated with recurrent symptoms of acute poisoning. Impaired lung function and asthma symptoms are considered to be the main effects of exposure to inhalable fraction. Due to the limited number of the available data it is not possible to assess carcinogenicity, reproductive toxicity and teratogenicity of zinc and its compounds. The aim of the study was to analyze the major health hazards resulting from occupational exposure to zinc and its inorganic compounds in the context of their physico-chemical properties, a wide range of applications and occupational exposure data. Med Pr 2017;68(6):779-794.

含氟、砷氧化锌烟灰制备活性氧化锌

以氧化锌烟灰为原料，采用NH3-NH4Cl溶液浸出，浸出液采用FeCl3作为除砷剂进行除砷，采用CaCl2作为除氟剂进行除氟，再经锌粉置换除杂和活性炭吸附处理后，采用浓盐酸调节pH进行沉锌、进而进行二次加水水解转化和煅烧以制备活性氧化锌。研究结果表明，在NH4Cl浓度4mol/L、NH3•H2O浓度2mol/L、浸出温度50℃、浸出时间1h的浸出条件下，锌的浸出率达到98%以上。当nFe/nAs= 5时，FeCl3作为除砷剂除砷率达到99.7%；当nCa/nF= 1时，CaCl2作为除氟剂除氟率达到98.5%。采用浓盐酸调节pH至6.70时，Zn(NH3)2Cl2沉淀的析出率达到最大，为82.85%。Zn(NH3)2Cl2沉淀物经一次水解转化得到Zn(OH)1.6Cl0.4，经二次水解转化得到Zn(OH)2，再经500℃煅烧2h后可得活性氧化锌，产品质量均达到HG/T2572-2012标准指标，锌的直收率达80%以上。 Zinc oxide fume dusts as raw material were leached with NH3-NH4Cl solution. The arsenic and flu-orine in leaching solution were removed with FeCl3 and CaCl2 respectively. After the zinc powder displacement process and activated carbon adsorption treatment, precipitation of Zn(NH3)2Cl2 was carried out by adjusting the pH value of leaching solution with concentrated hydrochloric acid. Then active zinc oxide was prepared from two-step hydrolytic conversion of Zn(NH3)2Cl2 followed by calcination. The results show that the zinc leaching rate is more than 98% at the condition of 4 mol/L NH4Cl, 2 mol/L NH3•H2O, leaching temperature and leaching time of 50˚C and 1 h. The re-moval rates of arsenic and fluorine are 99.7% and 98.5% respectively when the molar ratio of Fe to As is 5 and Ca to F is 1. The precipitation rate of Zn(NH3)2Cl2 reaches its maximum, which is 82.85% at pH = 6.7. The products of two-step hydrolytic conversion are Zn(OH)1.6Cl0.4 and Zn(OH)2 in sequence. Active zinc oxide is finally obtained by calcination at 500˚C for 2 hours. The quality of product is up to the standards of HG/T2572-2012 and the direct recovery rate of zinc is above 80%.

Removal of F and Cl from Zinc Oxide Fume from Fuming Furnace by Microwave Roasting

The work addresses the removal effectiveness of F and Cl in the zinc oxide fume produced in fuming furnace, by application of microwave roasting, taking advantage of the difference in microwave absorbing characteristics of halides, lead and zinc oxides in combination with the advantage of selective microwave heating. The effectiveness of defluorination and dechlorination was discussed in detail addressing the effect of all the influencing parameters such as roasting temperature, holding time and stirring speed. SEM and XRD were utilized to understand the removal mechanism of F and Cl. The results show that a nearly 92.8 % defluorination efficiency and 90.3 % dechlorination efficiency could be achieved at roasting temperature of 700 °C, holding time of 80 min and stirring speed at 120 rpm, satisfying the requirements of the wet smelting electrolysis process.

Response surface optimization of process parameters for the removal of F and Cl from zinc oxide fume by microwave sulphating roasting

Microwave sulphating roasting was applied to zinc oxide fume from a fuming furnace for the removal of F and Cl. The effect of important parameters such as roasting temperature, holding time. and vapour flow were investigated and the process conditions were optimized using response surface methodology. The results showed that the effects of roasting temperature and holding time on the removal efficiency of F and Cl were most significant, and the effect of vapour flow is of much lower importance. The defluorination and dechlorination efficiency increased rapidly as the roasting temperature and holding time increased, while the vapour flow had little effect. The defluorination efficiency could reach 91.3% while the dechlorination efficiency could reach 89.5%, under the process conditions of roasting temperature 655°C, holding time 65.2 minutes, and vapour flow of 6.8 ml/min. The results showed that the removal of F and Cl from zinc oxide fume using a microwave direct roasting process is feasible and reliable.

Response surface optimization of process parameters for removal of F and Cl from zinc oxide fume by microwave roasting

Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The results show that the effects of roasting temperature and holding time on the removal rate of F and Cl are the most significant, and the effect of stirring speed is the second. The defluorination rate reaches 92.6% while the dechlorination rate reaches 90.2%, under the process conditions of roasting temperature of 700 °C, holding time of 80 min and stirring speed of 120 r/min. The results indicate that the removal of F and Cl from fuming furnace production of zinc oxide fumes using microwave roasting process is feasible and reliable.

Removal of Fluorides and Chlorides from Zinc Oxide Fumes by Microwave Sulfating Roasting

AbstractDechlorination and defluorination from zinc oxide dust by microwave sulfating roasting was investigated in this study. According to proposed reactions in the process, detailed experiments were systematically conducted to study the effect of roasting temperature, holding time, air and steam flow rates on the efficiency of the removal of F and Cl. The results show that 92.3% of F and 90.5% of Cl in the fume could be purified when the condition of the roasting temperature of 650 °C, holding time at 60 min, air flow of 300 L/h and steam flow of 8 ml/min was optimized. Our investigation indicates that microwave sulfating roasting could be a promising new way for the dechlorination and defluorination from zinc oxide dust.

Diagnosing metal fume fever--an integrated approach

Exposure to high concentrations of zinc oxide fume can cause metal fume fever (MFF). Two cases occurring following the oxy-acetylene cutting of galvanized steel frames are reported. To show that integrated working is valuable as secondary health care staff may not be familiar with MFF. Site visits by Her Majesty's Medical, Health and Safety (H&S) and Specialist Occupational Hygiene Inspectors to gather information and cooperation with occupational health, primary and secondary health care staff to diagnose MFF. Poor exposure control caused metal fume inhalation in these cases. Multidisciplinary working established diagnosis, causation and compliance with H&S legislation. Risk assessments are required to identify health risks and to determine required exposure control measures. Failure to do this resulted in an unusual case of MFF leading to hospital admission. Diagnosis can be delayed if a full occupational history is not taken. Successful investigation of such cases benefits from collaborative working.

Metal fume fever presenting as aseptic meningitis with pericarditis, pleuritis and pneumonitis

Metal fume fever (MFF) is a well-known complication of zinc oxide fume inhalation. Prompt recognition of this condition is essential for the proper medical management of this self-limited disease. To present a unique and unusual case of MFF. Our patient is a 25-year-old male welder who had MFF and presented with aseptic meningitis with pericarditis, pleuritis and pneumonitis. To our knowledge, this is the first case of MMF presenting with these signs and symptoms. MFF can present with a systemic inflammatory response causing a multi-organ serositis. Our case highlights the utmost importance of obtaining an occupational history on all our patients, even if they are critically ill.

Metal Fume Fever Presenting as Aseptic Meningitis with Pericarditis, Pleuritis, and Pneumonitis

Background Metal fume fever (MFF) is a well-known complication of zinc oxide fume inhalation. Prompt recognition of this condition is essential for the proper medical management of this self-limited disease. Aim To present a unique and unusual case of MFF. Results Our patient is a 25-year-old male welder who had MFF and presented with aseptic meningitis with pericarditis, pleuritis and pneumonitis. To our knowledge, this is the first case of MMF presenting with these signs and symptoms. Conclusions MFF can present with a systemic inflammatory response causing a multi-organ serositis. Our case highlights the utmost importance of obtaining an occupational history on all our patients, even if they are critically ill.

Study of the presence of fluorine in the recycled fractions during carbothermal treatment of EAF dust

Carbothermal treatment tests of electric arc furnace dusts (EAFD) using the Waelz kiln process were carried out in pilot-scale for the production of zinc oxide. The association of halides in the EAFD, and the recycled products, such as zinc oxide fumes and high-grade iron contents fractions were examined by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. XRD reveals the presence of chlorine and fluorine in the dusts in the form of KCl, NaCl and CaF 2. An ultra-pure fraction of zinc was obtained after the Double Leaching Waelz Oxide (DLWO) process was performed on the zinc oxide fumes. The halide contents were reduced to approximately 100 ppm Cl and 700 ppm F. The rest of these elements are in the form of CaF 2. About 65% F is volatilised as lead and zinc fluorides, 15% is expected in the magnetic fractions and 20% in non-magnetic fractions as CaF 2 and MnF 2, respectively.

Development of pulmonary tolerance in mice exposed to zinc oxide fumes.

As a result of repeated exposures to inhaled toxicants such as zinc oxide (ZnO), numerous individuals acquire tolerance to the exposures and display reduced symptoms. To ascertain whether tolerance is developed in an animal model, NIH-Swiss mice were exposed to 1.0 mg/m(3) ZnO for 1, 3, or 5 days (1X, 3X, or 5X), and polymorphonuclear leukocyte (PMN) and protein levels in bronchoalveolar lavage (BAL) were measured. Mice acquired tolerance to neutrophil infiltration into the lungs, as total PMNs returned near baseline in 5X-exposed animals as compared to that of the 1X exposure group (1X = 2.7 +/- 0.4 x 10(4), 5X = 0.2 +/- 0.1 x 10(4), mean +/- SE, p < 0.05). Development of tolerance to changes in lavageable protein, however, was not observed (1X = 313 +/- 29 microg/ml, 5X = 684 +/- 71 microg/ml, p < 0.05). Tolerance to PMN influx did not persist following re-exposure to ZnO after 5 days of rest. In contrast to ZnO exposure, following single and repeated exposure to aerosolized endotoxin there was development of tolerance to protein in BAL (1X = 174 +/- 71 microg/ml, 5X = 166 +/- 14 microg/ml, p > 0.05), but not to PMN influx (1X = 5.5 +/- 1.7 x 10(4), 13.9 +/- 1.7 x 10(4), p < 0.05). Induction of lung metallothionein (MT) was also observed in mice exposed once or repeatedly exposed to ZnO, suggesting that MT may play a role in its molecular mechanism.

Zinc exposure in Chinese foundry workers

Background: Inhalational exposure to zinc oxide fumes is associated with metal fume fever, a self-limited but very uncomfortable condition closely resembling influenza. Very little is known regarding the toxicokinetics of inhaled zinc, making the interpretation of zinc measurements in serum and urine problematic. Methods: Twenty workers in a zinc foundry in Baiyin, Peoples' Republic of China, were investigated with serial examinations by a physician, chest radiographs, and spirometry. Exposure assessment consisted of the measurement of zinc in serum, urine, and personal air samples. Results: No cases of metal fume fever were observed during the study period despite exposures to as high as 36.3 mg/m3 over less than 4 hr. In addition, no radiographic or functional changes were noted. Serum zinc levels of all workers were within the reference range and did not correlate with external exposure measurements. However, elevations were noted in urinary zinc levels, which showed a significant association (Spearman's correlation coefficient = 0.47, P = 0.04) between exposure to zinc and urine zinc. Conclusions: These results provide exposure measurements for zinc at which workers demonstrate tolerance to the development of metal fume fever. Furthermore, they suggest that urine may be the preferred biological medium for the assessment of zinc exposure. Am. J. Ind. Med. 35:574–580, 1999. © 1999 Wiley-Liss, Inc.

Zinc exposure in Chinese foundry workers.

Inhalational exposure to zinc oxide fumes is associated with metal fume fever, a self-limited but very uncomfortable condition closely resembling influenza. Very little is known regarding the toxicokinetics of inhaled zinc, making the interpretation of zinc measurements in serum and urine problematic. Twenty workers in a zinc foundry in Baiyin, Peoples' Republic of China, were investigated with serial examinations by a physician, chest radiographs, and spirometry. Exposure assessment consisted of the measurement of zinc in serum, urine, and personal air samples. No cases of metal fume fever were observed during the study period despite exposures to as high as 36.3 mg/m3 over less than 4 hr. In addition, no radiographic or functional changes were noted. Serum zinc levels of all workers were within the reference range and did not correlate with external exposure measurements. However, elevations were noted in urinary zinc levels, which showed a significant association (Spearman's correlation coefficient = 0.47, P = 0.04) between exposure to zinc and urine zinc. These results provide exposure measurements for zinc at which workers demonstrate tolerance to the development of metal fume fever. Furthermore, they suggest that urine may be the preferred biological medium for the assessment of zinc exposure.

Early Pulmonary Cytokine Responses to Zinc Oxide Fume Inhalation

Zinc oxide inhalation causes metal fume fever, a flu-like syndrome common among welders. Proinflammatory pulmonary cytokines play a role in mediating this occupational illness. The goal of this investigation was to characterize early pulmonary cytokine responses after experimental human exposure to inhaled purified zinc oxide fume. We quantified bronchoalveolar lavage (BAL) cytokine concentrations in 15 healthy volunteers 3 hr after inhalation of zinc oxide fume. We compared postexposure cytokine responses with postsham exposure responses in the same 15 subjects. We also compared cytokine responses with those of 14 “late follow-up” subjects previously studied by BAL 20 hr after zinc oxide fume exposure. Zinc oxide exposure was a statistically significant, dose-dependent predictor of increases in BAL TNF (mean exposure–sham difference ± SE = 9.5 ± 3.6 pg/mL,P= 0.02), IL-6 (mean exposure–sham difference ± SE = 5.5 ± 1.8 pg/mL,P= 0.009), and IL-8 (mean exposure–sham difference ± SE = 64.1 ± 23.9 pg/mL,P= 0.02). The TNF response was significantly greater at 3 hr follow-up compared with 20 hr follow-up, after adjusting for smoking status, zinc dose, and BAL macrophages (P= 0.004). Our findings provide evidence for a pulmonary inflammatory response 3 hr after inhalation of zinc oxide fume characterized by dose-dependent increases in BAL proinflammatory cytokine concentrations. These data indicate that TNF plays an important initial role in mediating metal fume fever.

Cytokines in Metal Fume Fever

Metal fume fever is a flulike illness caused by zinc oxide inhalation and accompanied by an impressive pulmonary cellular response. We hypothesized that the syndrome is mediated by cytokines released in the lung after exposure to zinc oxide fume. We carried out 26 experimental welding exposures in 23 volunteer subjects, performing postexposure bronchoalveolar lavage (BAL) 3 h (n = 6), 8 h (n = 11), or 22 h (n = 9) after exposure. We detected tumor necrosis factor (TNF), interleukin-6 (IL-6), and interleukin-8 (IL-8) varying in a time- and exposure-related manner. The concentration of TNF in the BAL fluid supernatant was significantly greater at 3 h than at 8 h or 22 h after exposure (p < 0.05), exhibiting a statistically significant exposure-response relationship to airborne zinc at each follow-up time period (p < 0.05). TNF concentrations were statistically correlated with those of IL-6 in BAL supernatant obtained at 22 h (r = 0.78, p = 0.01) and with concentrations of IL-8 in BAL 8 h after exposure (r = 0.85, p = 0.001). IL-6 displayed a significant exposure-response relationship to zinc (p < 0.05) at 22 h. IL-8 exhibited a significant exposure-response relationship to zinc (p < 0.05) at 8 h after exposure, a time at which IL-8 correlated with marked increases in BAL fluid polymorphonuclear leukocytes (PMN) (r = 0.7, p = 0.01). Although we also detected interleukin-1 (IL-1) in BAL samples, this cytokine did not demonstrate a statistically significant exposure response. TNF, IL-6, and IL-8 in BAL fluid supernatant concentrations increased in a time and exposure-dependent fashion after zinc oxide welding fume exposure. The time course of increased cytokines, their correlations with one another and with PMN in the BAL fluid, and the consistency of our findings with the known kinetics and actions of these cytokines support the hypothesis that a network of cytokines is involved in the pathogenesis of metal fume fever.

Utilizing Iron Residues from Zinc Production in the U.S.S.R.

When zinc calcine leach residues are subjected to conventional hydro-metallurgical treatment, iron is removed from the production circuit in the form of jarosite or goethite. A combined hydrometallurgical treatment of zinc calcine and zinc oxide fume leach residues applied at a zinc plant in the U.S.S.R. produces potassium jarosite containing undesirable impurities of 1.5–2.0 wt.% Zn, 0.2–0.3 wt.% Cu, 0.2–0.6 wt.% Pb, 0.005–0.01 wt. % Cd and 27–29 wt. % Fe. After some study, it was found that low-contaminant jarosite can be used in iron-oxide pigments and in cement clinker production. Methods for manufacturing such products have been developed and tested on a pilot-plant scale, and commercial tests are in progress. The investigations carried out for low-contaminantjarosite utilization resulted not only in the development of a wasteless and environmentally acceptable technology for zinc calcine treatment, but made it possible to recover one more valuable component—iron—from zinc raw materials.

Respiratory response of guinea pigs to zinc oxide fume.

Guinea pigs were exposed for 1 hr to submicrometer zinc oxide fume at a concentration of approximately 1 mg/m3. Measurement of pulmonary mechanics was used to assess the response. The exposure produced a slight decrease in compliance which was statistically significant. The compliance showed a further decrease 1 hr post-exposure. In a second group of animals observed for two hours after exposure a progressive decrease in compliance was observed between the first and second post-exposure hours. No changes were observed in resistance, tidal volume, frequency, or minute volume.

Respiratory response of guinea pigs to zinc oxide fume

Respiratory response of guinea pigs to zinc oxide fume

Effect of the inhalation of zinc and dietary zinc on paraquat toxicity in the rat

A possible pharmacological effect of zinc against the pulmonary toxicant paraquat has been studied. Rats were treated with zinc either by inhalation of zinc oxide fume aerosol or consumption of zinc supplemented food. The animals were then injected with paraquat ip (30 mg/kg) and lethality monitored for 7 days. Neither zinc inhalation nor dietary zinc protected the animals against paraquat-induced lethality. In fact, exposure of rats to zinc oxide fume aerosol potentiated the lethal effects of paraquat. The mechanism of paraquat-induced lung toxicity at the cellular level does not appear to directly involve a zinc-dependent step. This distinguishes paraquat from other injurious agents which have been reported to respond to zinc.