Sulfuric Acid Manufacture Research Articles

Sustainable synthesis of vanadate/fluorapatite nano-crystallites from solid waste for enhanced photocatalysis and pollution removal

In this work, vanadate-fluorapatite, V2O5/Ca10(PO4)6F2, nanocrystals were successfully synthesized through a straightforward one-step co-precipitation method. This method was based on two toxic solid wastes, which are mainly generated as by-products during sulfuric acid manufacturing and in the phosphate industry. The two solid wastes were mainly based on phosphogypsum as a source of calcium and vanadium pentoxide as a source of vanadate. In comparison to numerous conventional methods for FAP synthesis, this innovative method is not laborious, not complex, cost-effective, and environmentally friendly, thanks to the recovery of toxic solid wastes. Furthermore, it consists of mixing various contents of anhydrous gypsum with phosphoric acid, vanadium pentoxide, and ammonium fluoride at one time and at room temperature with no further adjustment of the pH. Several physicochemical characterization techniques were used, including X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Ultraviolet-Visible Spectroscopy (UV-vis). Whereas SEM analysis of the crystals obtained showed a nanometer-scale fluorapatite crystallites was obtained. The obtained results offer exciting potential for applying the prepared nanomaterial in both photocatalysis and pollution removal. They hold great promise and are expected to generate significant interest in these fields.

Anodic protection of 316L stainless steel piping in sulfuric acid service: failure causes and remedial actions

Abstract Anodic protection (AP) is one of the corrosion control methods that has been widely used in the manufacture, storage, and transport of sulfuric acid. The present paper gives a brief review of the history, some applications, and a case study of failure causes and remedial actions of AP in a sulfuric manufacturing plant. The AP system consists of a direct current source, cathodes, reference electrodes, and signal conditioning electronics. In a sulfuric manufacturing plant, for AP of 316L piping (as an anode), platinized titanium (Pt/Ti) and Hastelloy B-2 were used as reference and cathode electrodes, respectively. After seven years of operation of the AP system in the sulfuric acid plant, a section of the protected pipelines has severely corroded. The study of the system showed that the reference electrodes, which were titanium-electroplated with platinum, lost their stability in the acid with the loss of coating and caused overprotection. However, the system could not control the pipe’s potential in the AP situation. In this condition, accelerated corrosion of the cathodes and pipes has also occurred.

Synthesis and characterization of pyrite mineral from rock deposits in Bantimurung Maros Regency of South Sulawesi

The study has successfully obtained the mineral pyrite (iron pyrite persulfide) and Hematite (Fe2O3) of the natural resources in the Bantimurung District, Maros, South Sulawesi. The method used in this purification is the hydrothermal method. Based on the characterization results, it was obtained pyrite mineral with high purity (more than 90%). Based on the analysis, this material has a cubic structure P a -3 with lattice parameters a = 5.4167 Å and a space structure for the hematite group -R 32 c with lattice parameters a = 5.048 Å, b = 5.048 Å, and c = 13,762 Å. These results are consistent with the surface morphology characterized using SEM with various magnifications showing uneven particle distribution with a particle size of 5 µm-100 nm. The results of characterization and analysis of XRF and XRD show that the degree of crystallization and homogeneity of natural material deposits in Bantimurung are rich in iron, magnesium (Mg), sulfur (S), which appear with a high percentage, and high value minerals such as molybdenum (Mo) and neodymium with a low percentage. With this composition, the materials in Bantimurung have the potential to be used as photovoltaic coatings in solar cell applications, production of sulfur dioxide, paper industry, manufacture of sulfuric acid, semiconductor materials, and applications in sodium and lithium batteries.

Leaching of vanadium, potassium, and iron from spent catalyst of the manufacture of sulfuric acid

The sulfuric acid industry produces large volumes of spent catalyst containing vanadium. To develop an efficient method for vanadium recovery, hydrogen peroxide was used to oxidize sulfur in the spent catalyst, forming sulfuric acid, which, in turn, leached the metals from the catalyst. Experimental results showed that the leaching efficiency of vanadium gradually increased with hydrogen peroxide concentration; other parameters had minor effects. The hydrogen peroxide concentration, stirring rate, and pH had negative effects on leaching percent of potassium. Leaching efficiency of iron decreased with an increase in leaching time, stirring rate, and pH; with the increase in hydrogen peroxide concentration and liquid:solid ratio, leaching efficiency of iron first increased and then decreased. The optimum leaching conditions for vanadium were hydrogen peroxide concentration of 148 g/L, leaching time of 5 min, leaching temperature of 25 °C, stirring rate of 300 r/m, and liquid:solid ratio of 3:1, and leaching efficiencies of vanadium, potassium, and iron were 92.2%, 48.2%, and 46.3%, respectively. For potassium and iron, the leaching efficiencies of 70.9% and 70.5% were achieved using pure water leaching under the conditions of leaching time of 30 min, liquid to solid ratio of 4:1, and the temperature of 25 °C.

Vanadium removal from spent catalyst used in the manufacture of sulfuric acid by electrical potential application

Vanadium has many industrial applications and its contribution to environmental contamination is growing every day. Spent catalyst used in the sulfuric acid production is considered a hazardous residue due to the presence of vanadium pentoxide which is the most toxic form of the vanadium. Because of this, currently, these wastes are incinerated. Thus, the removal of vanadium from catalysts is justified from environmental and economic viewpoints. The aim of this work is to evaluate the effect caused by the application of the electrokinetic remediation technique in the removal of vanadium of spent catalyst used in sulfuric acid industry when submitted to different conditions of electrical potential. The experiments were performed under 6.7 and 20.0 V m−1 constant potential gradient. The results showed that the maintenance of a potential gradient of 20.0 V m−1 resulted in an increase of 16% in vanadium removal but an increase in energy consumption per kg of remediated catalyst of about 80 times compared to the application of 6.7 V m−1. It was also observed that the intensity of the applied electrical potential modify the pH of the medium.

On the study of industrial waste sites on the Karelian Isthmus/Russia using the RMT and CSRMT methods

Radiomagnetotelluric (RMT) and Controlled Source Radiomagnetotelluric (CSRMT) measurements were carried out on landfills of industrial wastes located on the Karelian Isthmus/Russia. The RMT and CSRMT data were interpreted using the 2D inversion techniques, and the 2D conductivity structures of the investigated industrial waste sites were derived. The RMT method is based on measurements of electromagnetic fields of remote radio transmitters in a frequency range of 10–1000 kHz or in a frequency range of 1–1000 kHz by using a controlled source (CSRMT method). A landfill in the settlement Morozova near St. Petersburg was formed as a result of a long-term warehousing of toxic wastes by the sulfuric acid manufacture. Soils and ground waters were polluted with salts of heavy metals. In the adjacent to the landfill territory, investigations were realized by the RMT method and a polluted zone was determined. This zone is traced up to the coast of the Ladoga Lake and the Neva River. It constitutes a potential danger because the Neva River is used for the water supply of St. Petersburg. Another landfill of debris in a former sandy career is located in the Vyborg area. The high conductivity and a relative large thickness of the wastes did not allow us to map the bottom of the landfill by the RMT method using the frequency range of 10–1000 kHz. Therefore, CSRMT measurements with an extended frequency range up to 1 kHz were carried out on this landfill, and the 2D inversion of the CSRMT data clearly showed the lateral and vertical extension of it.

Oxidative regeneration study of spent V2O5 catalyst from sulfuric acid manufacture

In this work, the efficiency of the regeneration process of spent V2O5 catalyst from sulfuric acid plant under different atmospheres (5%O2/N2 or air) was evaluated. Temperature-programmed results showed that the observed reduction profiles of the samples are attributed to the reduction of amorphous V+5 and low-valence V+5−x species at low temperatures followed by the reduction of their crystalline structures at high temperatures. Significantly low values of SO2 conversion of the spent samples can be explained by the significant drop in quantity of all vanadium species, coupled with their structural change to more thermally stable forms. It was found that the exposure of the spent catalyst to 5%O2/N2 stream at 550 °C for 1 h allowed at first the re-oxidation of amorphous low-valence V species and second the dissolution of crystalline low-valence V species, thus resulted in recovery of their catalytic activity for SO2 oxidation. However, the regeneration in air was less effective than in 5%O2/N2 stream. This is supposedly due to the differential behaviors of the spent sample in different oxidative streams toward re-oxidizing low-valence V species and re-dissolving V precipitates.

UTILIZATION OF SULFUR SLUDGE RESULTS FROM THE MANUFACTURING OF SULFURIC ACID IN A FILTER AID PRODUCTION

Sulfuric acid manufacture generates huge quantity of sulfur sludge causing major environmental problems in their storage and disposal. On the other hand, molten sulfur should be filtered for sulfuric acid production to remove solids that may plug sulfur spray nozzles or accumulate on catalyst beds that increasing the pressure drop and decreasing operating durations. In this study, attempts were carried out using sulfur sludge wastes a filler in the manufacturing of filter aid. The filter aid using sulfur sludge is compared with the other filter aids such as Kessel Gohar diatomite (global product) and ABU ZAABLE 12 “AB12” (local product). Results showed that the prepared filter aid using sulfur sludge as filler decreases the ash content in filtrated sulfur than Kessel Gohar diatomite and AB12 with a ratio of about 26.4% and 39.4%, respectively, and thus results in increasing the operating durations due to decreasing the amount of ash deposited in the catalyst beds compared with filter aids of Kessel Gohar diatomite and AB12 with a ratio of about 25.2% and 39.4% respectively. On the other hand, sulfur sludge filter aid also improves filter operating duration than Kessel Gohar diatomite and AB12 with a ratio of about -1.2% and 32.4% respectively. Finally, sulfur sludge filler in manufacturing of filter aid can be used as a reusable material without any change on the ash content in filtrated sulfur and filter operating duration.

Utilization of low-grade pyrite cinder for synthesis of microwave heating ceramics and their microwave deicing performance in dense-graded asphalt mixtures

Recycling of large stockpile of low-grade pyrite cinder, a solid waste consisting of hematite and halloysite from sulfuric acid manufacturing plants, will avoid increased stress on the environmental impact because of its difficulty for disposal. In this paper, the most appropriate experimental conditions of preparing microwave heating ceramics (MHCs) from low-grade pyrite cinder was investigated. Moreover, the potential use of MHCs as an aggregate of dense-graded asphalt mixtures with deicing capacity was also demonstrated in laboratory in light of low deicing efficiency of commonly used deicing methods. The results showed that under the following parameters, molding pressure 50 MPa, sintering temperature 1350 °C for 180 min, calcium fluoride 5% and coal powder to LPC ratio of 0.1, the microwave heating efficiency (MHE) of ceramics was approximately 24.0 times that of limestone and compressive strength of ceramics can reach up to 87.5 MPa. Microscopy analysis revealed that the principal strength-given mineral components in ceramic samples were plate-like mullite and bulk ferric oxides. The MHE of dense-graded asphalt specimens containing limestone aggregates totally replaced by MHCs, was 15.0 times that of specimens with no MHCs. The microwave deicing time (MDT) of dense-graded asphalt mixtures could be evidently shortened with the increasing volume of MHCs and increased with the thickness of ice. However, the MDT of specimens increased with the fall of surrounding temperature.

Comparison of pyrite cinder with synthetic and natural iron‐based oxygen carriers in coal‐fueled chemical‐looping combustion

AbstractPyrite cinder, a Fe2O3‐containing industrial waste derived from the sulfuric acid manufacturing industry, was compared with the synthetic and natural iron‐based oxygen carriers, to explore its potential superiority in coal‐fueled chemical‐looping combustion. The oxygen carriers were evaluated through a lab‐scale fluidized‐bed reactor regarding their reactivity, recyclability, and attrition performance. The results showed that pyrite cinder prevailed over synthetic and natural iron‐based oxygen carriers in terms of the reactivity. Similar CO2 yields were obtained by both pyrite cinder and synthetic Fe‐Al(10nm) oxygen carrier, but the char conversion rate for pyrite cinder was obviously higher than that of synthetic and natural iron‐based oxygen carriers. As for the cyclic reaction behavior, both pyrite cinder and natural MAC iron ore performed well regarding the stable yield of CO2, whereas synthetic Fe‐Al(10nm) oxygen carrier showed a poor resistance to the decay of reactivity and occurrence of severe sintering. The attrition performance of three oxygen carriers under different operation parameters showed that the particle collision and the collisions between oxygen carrier particle and reactor wall were the major triggers to the attrition. The cyclic attrition tests showed that the abrasion‐resistant capability for the pyrite cinder pelletized by the double‐roller squeezing granulation method was lower than that of synthetic and natural iron‐based oxygen carriers. It can be concluded that the pyrite cinder would be an outstanding candidate as the iron‐based oxygen carrier, but its mechanical strength should be enhanced before produced in large scale. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.

An Innovative Approach to Separate Iron Oxide Concentrate from High-sulfur and Low-grade Pyrite Cinders

High-sulfur and low-grade pyritc cinders are the waste products of sulfuric acid manufacturing plants. Many valuable components, such as iron oxide, are contained in pyrite cinders and difficult to be separated and purified just via the high temperature roasting process. Considering this, an innovative method including water-washing, aqua regia leaching, hydrothermal alkali activation and acid-washing was developed. And the effects of different parameters on recovery efficiency of iron oxide were systematically investigated. The optimum parameters were proposed as follows: water rinse-leaching at room temperature for 5 — 20 min, and melting at 160 °C for 2. Oh with NaOH (concentration of 30 mass%), followed by leaching with aqua regia solution (3. 0 vol. %) for 1. 0 h. After the treatment, the content of iron oxides increased from 54. 3 to 96. 0 mass% with the recovery rate exceeding 85%. Meanwhile, calcium sulphate was recovered as the high value-added products by alkali extraction liquid. Furthermore, the phase transformation and microstructure of the samples in the process were studied by physicochemical methods to reveal the separation mechanisms of different components in the pyrite cinders.

Recovery of Vanadium from Acid and Basic Leach Solutions of Spent Vanadium Pentoxide Catalysts

The vanadium pentoxide catalysts are used in the sulfuric acid manufacture, but as an inherent consequence of the process, they are deactivated or poisoned, because of that they need to be renewed. In Ecuador, the increase of environmental pollution concerns and the legislation related with the final dispose of hazardous residues is forcing to companies to process their waste products and residues. For the present investigation, catalysts samples were characterized using AAS (atomic absorption spectroscopy), XRD (X-ray diffraction), surface area (BET) and SEM-EDS (scanning electron microscopy). Results show presence of 6-5% w/w of vanadium pentoxide (V2O5), 10-11% w/w of potassium oxide (K2O) and 55-60% w/w of silicon oxide (SiO2). The material presents a pore size of 3 nm and a specific surface area of 200 m²/s. The spent catalyst was firstly pulverized in a powder mill until 200 µm was attempted, then a calcination at 450 °C was made. Different leaching agents were used: nitric, sulfuric, hydrochloric acid and sodium hydroxide with variation of percentage of solids, particle size, leaching agent concentration and leaching time. Sodium carbonate was added to the solution to obtain a precipitate. A final calcination step was made at 450 °C to obtain vanadium pentoxide. The best results were obtained by using sulfuric acid at 75 g/L, 20 w/w percentage solids, environmental temperature, agitation speed was maintained 750 rpm and 30 minutes leaching, the recovering vanadium rate was 94.41%. In the precipitation stage 92.2% of sodium meta vanadate, for that a pH 7 was required. Finally, precipitation was calcinated getting vanadium pentoxide at 97% purity and it costs is $104.5 per 500 grams.

Optimization of electrocoagulation operating parameters and reactor design for zinc removal: application to industrial Tunisian wastewater

This study was carried out to investigate the effect of the electrocoagulation reactor design parameters in the removal of zinc from water. In order to optimize experimental electrocoagulation reactor parameters such as inter electrode distance (die), electrode connection mode, surface-area-to-volume ratio (S/V), and the initial temperature of the solution (T), many electrocoagulation tests were performed using aluminum electrodes. The obtained experimental results showed that optimal zinc removal was achieved with a distance between electrodes of 0.5 cm, a bipolar connection mode, the surface-area-to-volume ratio (S/V) of 13.6 m−1, and for an initial temperature (T) of 50°C. The application of these results on the treatment of a sulfuric acid and superphosphate manufacturing industry wastewater made it possible to achieve a total zinc removal in five minutes of electrolysis time.

“Geber's Method” in Environmental Perspective Revisited

Excessive quantities of atmospheric sulfur dioxide (SO2) are environmentally problematic. One of the anthropogenic processes that release SO2 into the atmosphere is the contact process for the industrial manufacture of sulfuric acid (H2SO4). The progress of the idea to make use of “green vitriol” (FeSO4·7H2O) for “SO2-free” manufacture of H2SO4 is discussed here. The environmentally advantageous fact that the method, called “Geber's method,” can theoretically be “waste-free” is addressed in this “Comment,” and the challenge of having limited suitable resources of FeSO4·7H2O in the US for use as the starting material in “Geber's method” is emphasized.

Morphofunctional analysis of the prostate exposed to chemical manufacture factors.

The structural characteristics of the prostate and the blood flow in the organ were studied in chemical plant workers suffering from chronic prostatitis. The prostate echostructure was characterized by vast zones of fibrosis and calcinosis, the hemodynamic ultrasonic parameters were low. Degenerative changes in the acinar structures and stromal fibrosis predominated in the biopsy specimens, these shifts were the most pronounced in the peripheral and transitory zones. Foci of common and small-acinar degeneration of the glands, abundant concrements, and significant collagenization with periglandular and perivascular sclerosis without or with slight inflammatory infiltration were detected. We hypothesize that long exposure to adverse factors of sulfuric acid manufacture contributed to the development of pathological changes in the prostate.

Nicolas Clément

Nicolas Clément (1779-1841) was a brilliant chemist and entrepreneur, although he lacked a formal education. Alone, or in collaboration with his father-in-law, Bernard Desormes, he developed the theory of the manufacture of sulfuric acid by the lead chamber method, discovered the correct formula of carbon monoxide and carbon disulfide, and the composition of lapis lazuli, as well as carrying on the industrial manufacturing of alum, ferrous sulfate, alcohol, etc.

Sulfur Dioxide Production from Phosphogypsum: Thermodynamic Analysis and Experimental Results

Phosphogypsum or chemical gypsum is a by-product generated in the manufacture of phosphoric acid, generated in the proportion of 4 to 6 tons for every ton of acid produced by the fertilizer industry. Its reuse is important from the economic, social and environmental point of view. The purpose of this paper is to investigate the thermodynamic condition of sulfur dioxide recovering from thermal decomposition of phosphogypsum. The main advantage of this process is to return the sulfur dioxide to sulfuric acid manufacturing. In this case, sulfur demand by fertilizer industry and phosphogypsum generation could be greatly reduced. Experimental results were obtained from a lab scale rotary kiln. Theoretical approach and experimental setup were validated by using the actual data from thermal decomposition of limestone. Theoretical and experimental results showed the thermal decomposition of phosphogypsum is thermodynamically feasible only at high temperatures.

Study on Vanadium Recovery from Spent Catalyst Used in the Manufacture of Sulfuric Acid

Spent catalysts for sulfuric acid production have large amount of vanadium and due to environmental authority it is required to reduce the vanadium contain of the spent catalyst. Experimental investigation was conducted to study the vanadium recovery from spent catalyst via leaching process using sodium hydroxide to study the effect of process variables (temperatures, sodium hydroxide molarities, leaching time and particle size) on vanadium recovery. The effect of process variables (temperature, particle size,molarities of sodium hydroxide and leaching time) on the percentages of vanadium recovery were investigated and discussed .It was found that the percentage of vanadium recovery increased with increasing temperature up to 100 , increasing sodium hydroxide molarity from 2 to 4M, increasing leaching time, decreasing particle size from mesh 150, 100 and 65. A complete vanadium recovery was achieved at the following conditions: temperature (100˚c), particle size (150 mesh ) molarity of Na OH(4 molar) and leaching time(5 h).

Bacterial solubilization of phosphorus from phosphate rock containing sulfur-mud

Bacterial solubilization of phosphorus (P) from phosphate rock with acidophilic iron- and sulfur-oxidizing bacteria ( Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans) was carried out in shake flasks leaching experiments. Phosphate rock sample was supplemented with sulfur-mud (a waste of sulfuric acid manufacturing plant) containing significant amounts of elemental sulfur (S 0) and greigeite (Fe 3S 4, cubic) as an energy substrate for these acidophilic bacteria. Bacterial oxidation of sulfur and sulfur mineral was an acid-generating system. Biologically generated sulfuric acid (H 2SO 4) was produced which dissolved P from phosphate rock due to acid attack on fluorapatite mineral Ca 5(PO 4) 3F) present in rock matrix. The dissolution of P from phosphate rock was mainly attributed to the concentration of bacterially produced sulfuric acid in the leaching medium. A. ferrooxidans and A. thiooxidans solubilized significant amounts of P in bioleaching process. The mixed culture of these bacteria solubilized higher amounts of P (70.2% P 2O 5) at 10% pulp density during 40-days of leaching as compared with pure culture alone. The maximum P solubilzation rate of 564.8 mg P 2O 5 L –1 d –1 was achieved in leach solution inoculated with mixed culture. The dissolution of P was found to be pH-dependant phenomenon.

Effect of EDTA on the fractionation and uptake by Taraxacum officinale of potentially toxic elements in soil from former chemical manufacturing sites

The revised Community Bureau of Reference (BCR) sequential extraction procedure has been applied to investigate the effectiveness of two soil remediation strategies to reduce the amounts of potentially toxic elements in three contrasting contaminated soils (soils A, B and C) from derelict chemical manufacturing sites in the UK. Soil A was from the 35–45 cm deep layer of a site used for the manufacture of sulfuric acid. Soils B and C were topsoils from a site used for the manufacture of explosives, nitric acid and nylon The remediation strategies were flushing with EDTA in a column experiment (applied to soils A, B and C) and EDTA enhanced phytoremediation with Taraxacum officinale in pots (applied to soil B). Soil B, which contained the least amounts of aqua regia extractable metals, except for lead, but higher proportions of analytes in non-residual (i.e. acid exchangeable, reducible and oxidisable) forms was found to release greater amounts of analytes when flushed with EDTA. Comparison of the BCR sequential extraction fractionation patterns obtained before and after flushing of soil B, suggested that EDTA removed calcium mainly from the acid exchangeable pool, manganese mainly from the reducible pool, zinc from both acid exchangeable and reducible pools, and copper and lead from acid exchangeable, reducible and oxidisable pools. The chelate enhanced phytoremediation pot experiment conducted using soil B showed that EDTA treatment was significantly positively, correlated (p < 0.05) with an increase in the proportion of analytes recovered from the soil in step 1 of the BCR extraction scheme, for all analytes, and also enhanced metal uptake by plants. The sum of the amounts of analyte released in the first three steps of the sequential extraction, commonly regarded as the maximum amount of elements potentially available for plant uptake, was not positively correlated with plant-uptake.