Pickling Bath Research Articles

Temperature prediction for wire rod pickling plant management

The prediction of the temperature in the different tanks of a mixed acid pickling line of wire rod coils is described in this paper. The goal is to develop a robust model-based prediction tool that allows prospective development of pickling bath states and adjustments in the management of a pickling line. The temperature of the pickling bath is a critical variable for the efficiency of the pickling process. Excessive temperatures can have an unfavorable effect on the pickling results and can complicate the decontamination of the exhaust gases. Root mean square error values lower than 0.2∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{\\circ }$$\\end{document}C were obtained when treating martensitic and ferritic steels, which are precisely the most problematic types of steel in the control of pickling temperature. The model software was installed on a computer for online operation at the pickling plant. Relevant information is predicted and transmitted such as the temperature pickling bath trend with the sequence of the wire coils to be treated. Plant personnel are able to change this sequence or modify pickling retention times based on this information. The economic benefits come mainly from better use of the production line, reducing coil waiting times.Graphical abstract

The Production of Hematite Powder from Spent Pickling Hydrochloric Acid

This research aimed to study the recycling process and the feasibility of recovering iron as hematite or red oxide powder (Fe2O3) from spent pickling acid (hydrochloric acid). The spent hydrochloric acid waste from the pickling bath in the sheet rolling steel industry contains approximately 233 g of iron dissolved in one liter of the spent acid. To recover iron, 2 M NaOH was added to the spent acid until reaching pH 7. The iron was precipitated as iron oxide and/or hydroxide. Next, the oxidation of ferrous oxide was carried out by adding H2O2 35%v/v to control the shade color. The precipitates were subsequently separated from the acid solution by a filter press. The precipitates were dried at 110°C for 24 h and calcined at 700°C for 2 h to synthesize and modify the crystallinity of ferric oxide. Ferric oxide was subject to water washing, where contaminating sodium chloride could be dissolved and filtered out. After drying at 110°C for 24 h, high-purity hematite was achieved. Hematite recovered from the spent pickling acid via this process provided more than 97% purity at 94.4% recovery.

Surface analysis and interface properties of a newly synthesized quinoline-derivative corrosion inhibitor for mild steel in acid pickling bath: Mechanistic exploration through electrochemical, XPS, AFM, contact angle, SEM/EDS, and computational studies

The two novel heterocyclic quinoline derivatives, 5-(methoxymethyl)-2-methylquinolin-8-ol (QO) and 5-((2-hydroxyethoxy)methyl)-2-methylquinolin-8-ol (QOOH) are examined in this work for their ability to adsorb against the corrosion of mild steel (MS) in a molar hydrochloric acid (HCl) media. After the synthesis of these two compounds, we proceeded some analytical methods such as the nuclear magnetic resonance of the proton and the carbon (1H NMR and 13C NMR). Potentiodynamic polarization (PDP), electrochemical frequency modification (EFM), and impedance spectroscopy (EIS) were the methods used in the experimental examination. The results indicated that the inhibitory efficacy of QO and QOOH increases with concentration. Both inhibitors exhibit mixed type behavior, according to the findings of polarization. Following that order was QO's and QOOH's inhibitory efficiencies 93.20% (QO) > 88.84% (QOOH). The Langmuir adsorption model is used in the adsorption process of these two chemicals. A barrier layer encasing the MS was shown to exist by Scanning electron microscope (SEM), energy dispersive X-ray analysis (EDS), atomic force microscopy (AFM), contact angle, and X-ray photoelectron spectroscopy (XPS) were all used in the examination of the surface characterization. The Density functional theory (DFT) findings suggest that inhibitors with electron-accepting capabilities exhibit the strongest interactions with the iron surface.

Correlation between experimental and theoretical approaches in the performance of new epoxy resin as an effective corrosion inhibitor for mild steel in acid pickling bath

In this recent work, novelty epoxy resin namely 1,3,4,5,6-pentaglycidyloxy hexan-2-one (PGH) was synthesized characterized and studied as a potential anticorrosive protection for mild steel (MS) in 1 M HCl solution. The corrosion inhibition for MS was examined by “potentiodynamic” polarization (PDP), electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation measurements (EFM), scanning electron microscope coupled with energy dispersive X-ray spectroscopy (MES/EDS) and theoretical approaches (DFT and MD simulation). PGH elaborated was investigated by the Fourier transform infrared (FTIR) spectroscopy. Additionally, the inhibitory efficiencies found at higher concentration (10−3 M of the PGH) are 85.5% (EIS) and 88.6% (PDP), respectively. PDP results indicated that the PGH acted as a mixed-type inhibitor in 1 M HCl medium. SEM/EDS characterization represents a terrific decrease in corrosion of the MS surface within 10−3 M of PGH compared with the 1.0 M HCl pure. DFT calculation provided molecular level insights on the nature and the active centres of the corrosion inhibition efficiency of the PGH elaborated. MD simulation showed that the PGH has the maximum inhibition efficiencies at oxygen atoms.

PickT: A Decision-Making Tool for the Optimal Pickling Process Operation.

This research approaches knowledge gaps related to the pickling process dynamic modelling (the lack of predictability and simplicity of existing models) and answers the practical need for a software tool to facilitate the optimum process operation (by delivering estimations of the optimum corrosion inhibitor addition, optimum pickling bath lifetime, corrosion rate dynamic evolution, and material mass loss). A decision-making tool, PickT, has been developed and verified with the help of measurements from two different pickling experiments, both involving steel in hydrochloric acid. The first round of experiments lasted 336 h (each pickling batch duration was 24 h) and Cetilpyridinium bromide (CPB) was the corrosion inhibitor in additions from 8% to 12%. The collected dataset served for the tool development and first verification. The second round of experiments lasted 10 h (each batch duration was 2 h) and involved metformin hydrochloride (MET) in additions between 3.3 g/L and 10 g/L. This dataset served to test the transferability of PickT to other operating conditions in terms of corrosion inhibitor type, additions, batch duration and pickling bath lifetime magnitude. In both cases PickT results are in accordance with experimental findings. The tool advantages consist of the straightforward applicability, the low amount of field data required for reliable forecasts and the accessibility for untrained professionals from the industry.

Acid pickling of carbon steel

This study reviews the possibilities of recovering the pickling waters from carbon and galvanised steel. Acid pickling with hydrochloric acid (HCl) is the most widely used chemical process to remove iron oxides from the metal surface without any significant attack on the steel itself. The acid pickling bath contains mainly ferrous chloride (FeCl2) produced by the reaction between the steel and free hydrochloric acid. However, zinc chloride (ZnCl2) is also found in the pickling of carbon steel parts prior to galvanisation, as the hooks and tools used to hang the carbon steel parts are also galvanised and reuse again polluting with Zn the pickling waters. Pickling water recovery or recycling technologies primarily seek the reuse of HCl in two ways. Partially by recovering the unreacted HCl or fully by breaking the FeCl2 bond through Pyrolysis technologies such as fluidised bed and spray roasting which in turn produces another iron oxide by-product. However, the most common by-product produced by pickling water recovery and recycling technologies is ferric chloride (FeCl3), as it is a coagulant widely used in wastewater treatment. However, if the pickling water contains ZnCl2 or other metals, the production of FeCl3 becomes unattractive and the pickling water is neutralised and deposited in landfill sites. This study also discusses a wide range of technologies capable of recovering all or part of the pickling water, including galvanic pickling water, that are usually excluded from circular economy strategies.

Development of an Efficient Acid Pickling Bath for Hot-Rolled Steel Coil

Development of an Efficient Acid Pickling Bath for Hot-Rolled Steel Coil

Static sorption of heavy metal ions on ion exchanger in the presence of sodium dodecylbenzenesulfonate

The effect of sodium dodecylbenzenesulfonate (anionic surfactant) on removal of selected heavy metal ions such as copper(II), cobalt(II), zinc(II) and nickel(II) using Lewatit MonoPlus TP 220 were studied. The critical micellization of concentration in the system containing both heavy metal ions and the anionic surfactant was obtained (surface properties). The percentage removal of heavy metal ions in the system without the anionic surfactant was compared with that of heavy metal ions in the presence of the anionic surfactant of the concentration below (↓CMC) and above (↑CMC) (HCl—heavy metal ions—anionic surfactant systems). Moreover, Lewatit MonoPlus TP 220 was applied for the heavy metal ions removal from real wastewaters (used a pickling bath) originating from leaching of the heat-resistant nickel and cobalt alloys. The critical micellization of concentration values depends on the composition of solution, presence of hydrochloric acid and heavy metal ions. The presence of the surfactant improves slightly the removal efficiency of cobalt(II) and nickel(II) ions and deteriorates the zinc(II) removal efficiency. Lewatit MonoPlus TP 220 shows high affinity for copper(II) in the model and real wastewater solutions in the case of the systems without and with the anionic surfactant.

Novel Methodology for the Selection, Dosing and On-Line Control of Corrosion Inhibitors for Industrial Acid Pickling

A novel methodology based on electrochemical hydrogen permeation tests is proposed to study the efficiency of commercial inhibitors for industrial acid pickling of iron and mild steels. Weight loss measurements and hydrogen permeation tests have been carried out in order to compare the sensitivity of different techniques to variations of low inhibitor dosages. It has been found a close dependence between low amounts of filming inhibitors and hydrogen uptake in the metallic surface with related permeation currents. The high sensitivity of permeation currents may be very useful to establish and also control the optimum amount of active substances in industrial pickling baths, with related cost savings. The implementation of the proposed methodology to improve the control of industrial pickling plants is also envisaged, since it would be possible to improve both sensitivity and time response of experimental permeation curves.

Recovery of brines from cheese making using membrane distillation at lab and pilot scale

Brines are a problematic waste stream due to their high salinity. In cheese manufacturing, a salinity up to 220 g/l is used for the pickling bath. This waste stream is currently transported and treated externally at high costs. Membrane distillation is able to treat much higher salinities compared to the traditional desalination techniques. In this article, membrane distillation was therefore proposed as an alternative treatment technology, simultaneously allowing the recovery of the salts and the production of pure water. Microfiltration was successfully used as a pretreatment for the brines of two different companies. The denaturation temperature of the proteins was found at 65.5 °C and it was shown that the temperatures in the MD process should be below this temperature. Different membranes were explored at lab scale and module performance tests confirm the feasibility of MD at pilot scale for this application. Additionally, it was shown that the total water production costs are mainly affected by the availability of waste heat. Without waste heat, the lowest cost of 35 €/m3 is achieved for the 24 m2 modules, with a total thermal power demand of 34 kW. The costs for discharge of the brines are estimated at 50–150 €/m3, while the value of the salts recuperated equals 20 €/m3 distillate produced. Therefore, even when there is a low availability of waste heat, application of membrane distillation for the recovery of brines from cheese making is an economically viable and technically feasible alternative for external treatment.

Recovery of hydrochloric acid from galvanizing industrial effluents

ABSTRACTThe recovery of hydrochloric acid and its separation from iron, zinc and minor elements, in the galvanizing pickling baths, were studied by solvent extraction (SX) and distillation and by distillation and crystallization. Several extractants were tested, the tri-isooctyl amine, Alamine 308, the primary aliphatic amine Primene JM-T and the mixture of four trialkylphosphine oxides, Cyanex 923. Only Cyanex 923 enabled distillation. The results indicated the feasibility of the processes to treat a real effluent using Cyanex 923 and to obtain high HCl concentrations in the distillate (256–330 g/L).

Analytical Method to Monitor Industrial Pickling Baths Initially Constituted by HF, HNO<sub>3</sub>

The present study couples the acid/basis titration and the ICP analysis in order to monitor the concentrations of nitric and hydrofluoric acids, and presents into baths used to pickle alloys of titanium or stainless steel, largely employed in the aeronautic industry. The pickling of the alloys releases various metallic cations able to react with HF in order to lead to metal-fluoride complexes and free H+, the last being able to react with the basis. In this study, it was determined: the most significant correlations providing the number of the protons released by the complexation of the metallic cation by the fluoride. The proposed method based on: 1) these correlations; 2) the titration pH = f(VKOH) curves; and 3) the content of metallic cations determined by ICP, enables the monitoring of the content of HNO3 and HF into the pickling bath. Assuming that one bath was used for one type of alloy (alloys of Titanium for example, or alloys of stainless steel), then the proposed method appears providing reliable concentration values of both acids as well as metallic cations.

Brass Pickling Bath Waste Waters: Nitric Acid, Cu++, Zn++ and Pb++ Separation and Recycling by an Hybrid Process Diffusion Dialysis Cementation - Precipitation

Brass Pickling Bath Waste Waters: Nitric Acid, Cu++, Zn++ and Pb++ Separation and Recycling by an Hybrid Process Diffusion Dialysis Cementation - Precipitation

PERFORMANCE OF DIFFUSION DIALYSIS FOR PICKLING EFFLUENT OPERATING UNDER A HIGH FLOW RATE

Diffusion dialysis (DD) is a membrane separation process. The major driving mechanism is an ionic concentration gradient. An anion-exchange membrane (AEM) equipped with DD is efficiently used for purifying waste acid and metal ion separation. The goal of this laboratory-scale study is to investigate the efficiency of a diffusion dialyser (model HKY-001), which was equipped with an AEM (model DF120), to purify waste acid solution (sulphuric acid). This study was conducted with actual waste acid from a pickling bath of an electroplating manufacturer in Samut Prakarn Province. In the experimental tests, the operating parameters, such as time to reach equilibrium, feed flowrate, water to feed (Qwater/Qfeed) and type of stripping water, were varied. To examine the performance of this treatment unit, the concentration of H+ (mol.L-1), acid recovery (% as H+) and metal ion rejection (%) were monitored regularly. In conclusion, increasing the feed flow rate will likely decrease the H+ recovery (%). The rejection (%) of Zn, Mn and Pb is likely to increase with increases in the feed flow rate. A higher metal ion rejection (%) can be achieved at a lower water-to-feed ratio.

Purification of H2SO4 of Pickling Bath Contaminated by Fe(II) Ions Using Electrodialysis Process

We used in this work electrodialysis (ED) to remove the iron (II) ions of sulfuric acid pickling bath. This technique has proven very useful and effective in our study. Indeed, it allowed us to demonstrate the effect of various parameters (current density, the nature of the membrane and the concentration of Fe (II)) on the efficiency of the electrodialysis process. The results obtained show that the treatment rate increases with increasing the current density in the range 1 to 20mA.cm-2. However, increasing up to 30mA.cm-2 led to a clogging of the membrane, involving a substantial increase in the electrical resistance of the system. Moreover the increase in concentration of iron ions in the feed compartment to 52g.L-1 improves the purification rate 70.17%. The study of the influence of the membrane nature has shown that the CMX membrane more effectively than CMV and two Nafion 117 membranes.In parallel with the treatment process is also studied the possibility to refocus sulfuric acid was studied a removal mechanism iron ions and sulfates of the study define the solution for species that might exist in the system Fe - H2SO4 - H2O. It is clear from this analysis that the purification of the solution (Fe (II) -H2SO4) processing will be based on the elimination of Fe2+ ions and HSO−4−. A purification mechanism of the solution based on the transfer of species through the ion exchange membranes has been proposed.

Selective Separation and Recovery of Zinc and Lead from Galvanizing Industrial Effluents by Anion Exchange

The recovery of zinc and its separation from iron, hydrochloric acid, and minor elements in the galvanizing pickling baths were studied by anion exchange. The breakthrough curves demonstrated that the resins, Lewatit MonoPlus MP 500 and AMBERLYST A21, exhibit a greater capacity for zinc than for cadmium, copper, and lead. The results indicated the feasibility of operating the ion exchange process to treat a real effluent. During the loading, lead started eluting until its complete removal from the resin. Like this, a two-step removal solution is proposed, using two columns with Lewatit MonoPlus MP 500, for separating zinc and lead.

Macroscopic, thermodynamic, kinetic and microscopic study of nitric acid pickling of Elektron 21 (EV31A) magnesium alloy

The study of pickling of the EL21T6 substrate in a nitric acid bath firstly provided knowledge of the influence of the different experimental parameters (concentration of acid, temperature and stirring of the solution) in relation to the etching rate. This experimental part led to the choice of standard pickling (Tbath = 25 °C, moderate stirring (250 rpm), [HNO3] = 1.20 mol/L, duration of 2 min) so as to obtain constant removal of material, even after several uses of the pickling bath. SEM observations also confirmed that in these operating conditions, pickling concerns both the grains of the matrix and the precipitates of type Mg3(Nd, Gd), leading to uniform removal of material from the surface. Working from a number of assumptions, thermodynamic and chemical kinetic studies then allowed a pickling mechanism to be proposed and led to obtaining values for the corresponding kinetic parameters (order of reaction, constant of mean rate, activation energy) to be obtained.

Is pickling rate of A36 steel dependent on the saturation of the pickling bath in acidic sulfate media?

In metal processing, pickling baths containing sulfuric acid used to clean steel surfaces are assumed that are exhausted when the bath becomes saturated with ferrous sulfate at around 80–90g/L. At saturation, the bath is regarded as ineffective and is discarded as waste material. To our knowledge, however, there is no experimental evidence showing that saturation determines the exhaustion of the bath and stops the pickling reaction. We therefore tested whether ferrous sulfate saturation stops the pickling reaction by adding different amounts of ferrous sulfate to a 20% sulfuric acid pickling bath and analyzing the pickling rate of A36 steel. We found that pickling rates were similar in saturated baths containing ferrous sulfate concentrations as high as 300g/L. We have thus confirmed that the pickling rate depends primarily on the proton concentration of the bath.

Behaviour of tetramine inhibitors during pickling of hot rolled steels

To avoid the dissolution of steel in industrial pickling process, tetramine inhibitors are added to the pickling bath. This study is devoted to the understanding of the action mechanism of these inhibitors in hydrochloric and sulphuric baths on non-alloyed and alloyed steels. Pickling experiments and characterization with XPS, Raman and infrared spectroscopies have shown that inhibitors work only in acid media and leached out from the steel surfaces during the rinsing operation just after pickling. The effectiveness of inhibitors depends on the acid media and the temperature. Experimental data are consistent with a surface mechanism, i.e., the so-called “outer-sphere” adsorption.

A new approach to chromium concentration from salt mixture solution using nanofiltration

The possibility of increasing of chloride ions in permeate, with keeping high chromium(III) retention, during nanofiltration of salt mixture solution characterized by very low pH has been investigated. An influence of the initial chlorides concentration and the relationship between chlorides and sulfates concentration on permeate composition and chromium(III) concentration factor was analyzed. Based on the obtained results the initial chlorides (on level 12–16 gCl −/dm 3) and sulfates concentration as well as Cl −/ SO 4 2 - ratio (below 1) in the feed has been determined. The obtained results allowed to offer the new approach to nanofiltration of chromium tannery wastewater by the recirculation of part of permeate for obtaining the optimum feed composition. In this way the conducted nanofiltration of chromium tannery wastewater will enable the direct reuse of both retentate – recovered tanning bath (high concentration of chromium) and permeate – recovered pickling bath (high concentration of chloride ions).