Trapping nitrous gases during nitric acid leaching of sulfide concentrates

2021 ◽  
pp. 29-36
Author(s):  
E. Yu. Meshkov ◽  
N. A. Bobyrenko ◽  
I. A. Parygin ◽  
A. A. Soloviev
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Nitrogen Oxides ◽  
Nitrogen Oxide ◽  
Acid Leaching ◽  
Process Water ◽  
Nitric Acid Leaching ◽  
Concentrated Sulfuric Acid ◽  
Sulfide Concentrates ◽  
Nitrous Gases

Gas-air mixtures that form in nitric acid leaching of sulfide raw materials possess the following peculiarities making a negative impact on trapping of nitrogen oxides: elevated temperature, different oxidation level of nitrogen oxides, slow oxidation of NO in region of low concentrations, and instability of the resulting gas-air mixture flow. Therefore, well-known methods of trapping nitrous gases shall be adapted to specific sulfide raw material. We propose a process flow diagram for trapping nitrous gases formed during nitric acid leaching of sulfide concentrates at atmospheric pressure on the example of Zhezkazgan concentrate. The paper addresses theoretical aspects of the use of water-ore pulp, concentrated sulfuric acid, process water and alkaline agents for trapping nitrous gases, and typical reactions of interaction of the proposed absorbents with nitrogen oxides. The choice of water-ore pulp as an absorber was made because of similarity between the mechanism of absorption of nitrogen oxides for neutral and alkali ore suspensions and the one for alkali solutions: nitrogen dioxide and nitrous anhydride are absorbed with formation of a solution of nitrates and nitrites. Due to availability in a liquid phase of ferrous iron along with NO2 and N2O3, acidic suspensions are also capable to absorb nitric oxide, to some extent, with formation of Fe(NO)SО4 complex. Process water absorbs only nitrogen dioxide, with formation of nitric and nitrous acids. Nitrous acid is an unstable compound in acidic environments and decomposes with formation of water and nitrogen oxide. At the stages of trapping nitrogen oxides with water-ore pulp and process water (circulating solution), it is recommended conditioning of gas-air mixtures by choosing the volume of additionally introduced air, in an amount to provide the highest rate of nitrogen oxide oxidation. At the stages of sulfuric acid and alkaline trapping of nitrogen oxides, it is recommended conditioning of gas-air mixtures by selecting the volume of additionally introduced air and the oxidation time of nitrogen oxide that provide an equimolecular mixture of NO and NO2. A distinctive feature of the use of water-ore pulp, concentrated sulfuric acid, process water and alkaline agents for trapping nitrous gases is possibility to use the products of absorption at the stage of sulfide concentrate leaching. The extended tests of trapping nitrous gases have been conducted. The plant capacity by the gas-air mixture ranged 17–21 m3/h, and by leached concentrate — 12–15 kg/h. In this case, the degree of capturing nitrous gases reached 96.8%. Return of the products of absorption of nitrous gases in the form of condensate, water-ore pulp, nitrosyl sulfuric acid, nitric acid solution, nitritenitrate lye allows to reduce the nitric acid consumption by 7–10 times relative the values obtained without using the trapping system. In this case, the degree of copper extraction into the leaching solution was 97.7%. The extraction degree of silver, rhenium, zinc was respectively 98.0%, 99.0%; 98.5%.

Electrochemical Aspects of the Nitric Acid Leaching of Lead Sulfide Concentrates: on the Way to a Highly Effective Method for Pb Recovery

2019 ◽  
Vol 2 (3) ◽  
pp. 221-230
Author(s):  
Yuri L. Mikhlin ◽  
Alexander Kholmogorov ◽  
Gennady Pashkov ◽  
Elena Mikhlina
Keyword(s):  
Nitric Acid ◽  
Lead Sulfide ◽  
Acid Leaching ◽  
Nitric Acid Leaching ◽  
Highly Effective ◽  
Sulfide Concentrates ◽  
The Way

Laboratory tests of the hydrometallurgical method for processing polymetallic raw material in Central Kazakhstan

2021 ◽  
pp. 92-98
Author(s):  
N. A. Bobyrenko ◽  
E. Yu. Meshkov ◽  
A. A. Soloviev ◽  
S. V. Zakharyan
Keyword(s):  
Nitric Acid ◽  
Redox Potential ◽  
Acid Leaching ◽  
Single Stage ◽  
Raw Material ◽  
Two Stage ◽  
Nitric Acid Leaching ◽  
Leaching Experiment ◽  
Nitrous Gases ◽  
Counter Current

Within the scop e of this study the leaching process of Cu, Zn, Co, Mo from the complex polymetallic sulfide concentrate with high Fe, As, which was produced in Central Kazakhstan using two methods is examined. The metal concentrations in the concentrate were 0.27% Cu, 0.026% Zn, 0.464% Co, 0.057% Mo, 15.51% Fe, 7.38% As. Nitrogen oxides formed in the processes of leaching were absorbed with water, the return of absorption product to the operation of leaching allowed reducing the consumption of nitric acid. The single-stage nitric acid leaching experiment was carried out at the leach concentrate productivity of 170±20 g/h, 80±2 °С, liquid/solid mass ratio (L/S) 6/1, leach time of 10.7 h, and nitric acid (57%) consumption of 0.12±0.01 l/h. The degree of capture of nitrous gases reached 97.8%. In these conditions Cu, Zn, Co, Mo, Fe, As were obtained with dissolution efficiencies of 96.98, 64.92, 99.99, 95.39, 80.13 and 99.80% respectively. Concentrations of NO3–, H+ and redox potential in the leachate were 88.7 g/l, 1.82 mol./l and 741 mV, respectively. The two-stage counter-current nitric acid leaching experiment was carried out at the leach concentrate productivity of 170±20 g/h, 80±2 °С, L/S 6/1, leach time of 26.8 h, and nitric acid (57%) consumption of 0.06±0.006 l/h. The degree of capture of nitrous gases reached 97.8%. In these conditions Cu, Zn, Co, Mo, Fe, As were obtained with dissolution efficiencies of 99.11, 85.23, 100.00, 88.60, 77.24 and 85.56%, respectively. Concentrations of NO3–, H+ and redox potential in the leachate were 46.7 g/l, 0.35 mol/l and 658 mV, respectively. Compared to single-stage leaching, two-stage counter-current nitric acid leaching allo ws the significant economy of nitric acid (256 g of 100% HNO3 per kilogram of concentrate), which is reduction of 48%. Moreover, counter-current leaching enables reduction in concentrations of NO3–, H+ and redox potential in the leachate. The further studies should focus on possible reduction in nitric acid consumption by lowering concentration of NO3– in leachate. The authors appreciate participation of I. A. Parygin, VNIPIpromtekhnologii in this study.

Gallium Arsenide Integrated Circuits Decapsulation Technique Using Mixed Acid Chemistry For Die-Level Failure Analysis

2018 ◽  
Author(s):  
Harold Jeffrey M. Consigo ◽  
Ricardo S. Calanog ◽  
Melissa O. Caseria
Keyword(s):  
Gallium Arsenide ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Integrated Circuits ◽  
Failure Analysis ◽  
Mixed Acid ◽  
Optimum Parameters ◽  
Plastic Package ◽  
Fuming Nitric Acid ◽  
Concentrated Sulfuric Acid

Abstract Gallium Arsenide (GaAs) integrated circuits have become popular these days with superior speed/power products that permit the development of systems that otherwise would have made it impossible or impractical to construct using silicon semiconductors. However, failure analysis remains to be very challenging as GaAs material is easily dissolved when it is reacted with fuming nitric acid used during standard decapsulation process. By utilizing enhanced chemical decapsulation technique with mixture of fuming nitric acid and concentrated sulfuric acid at a low temperature backed with statistical analysis, successful plastic package decapsulation happens to be reproducible mainly for die level failure analysis purposes. The paper aims to develop a chemical decapsulation process with optimum parameters needed to successfully decapsulate plastic molded GaAs integrated circuits for die level failure analysis.

scholarly journals Nitric acid leaching of polymetallic middlings of concentration

2013 ◽  
Vol 54 (6) ◽  
pp. 440-442 ◽  
Author(s):  
D. A. Rogozhnikov ◽  
S. V. Mamyachenkov ◽  
S. V. Karelov ◽  
O. S. Anisimova
Keyword(s):  
Nitric Acid ◽  
Acid Leaching ◽  
Nitric Acid Leaching

scholarly journals Research of Polymetallic Sulfide Industrial Waste Nitric Acid Treatment

2017 ◽  
Vol 2 (2) ◽  
pp. 174
Author(s):  
Rogozhnikov D.A. ◽  
Dizer O.A. ◽  
Shoppert A.A.
Keyword(s):  
Nitric Acid ◽  
Industrial Waste ◽  
Mutual Influence ◽  
Acid Leaching ◽  
Raw Material ◽  
X Ray Diffraction ◽  
Mathematical Methods ◽  
X Ray ◽  
Nitric Acid Leaching ◽  
Kinetic Features

<p>Thermodynamic and kinetic features studies of polymetallic sulfide industrial waste nitric acid leaching were carried out. Elemental and phase composition of investigated raw material were studied with X-ray diffraction and electron microscopy methods. Calculations of the Gibbs energy change for the likely reactions of sulfide minerals with nitric acid were performed. In order to determine the most probable conditions of the sulfide industrial waste leaching in nitric acid, as well as the mutual influence of the produced pulp components on the performance of the process, the kinetics evaluation of multicomponent sulfide industrial waste in a nitric medium was studied using mathematical methods.</p>

Electronic Warfare: Electrophilic Substitution

Reactions ◽  
2011 ◽  
Author(s):  
Peter Atkins
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Electrophilic Substitution ◽  
Proton Acceptor ◽  
Acid Molecule ◽  
Electronic Warfare ◽  
Hexagonal Ring ◽  
Initial Outcome ◽  
Concentrated Sulfuric Acid ◽  
Electron Clouds

Benzene, 1, is a hard nut to crack. The hexagonal ring of carbon atoms each with one hydrogen atom attached has a much greater stability than its electronic structure, with an alternation of double and single carbon–carbon bonds, might suggest. But for reasons fully understood by chemists, that very alternation, corresponding to a continuous stabilizing cloud of electrons all around the ring, endows the hexagon with great stability and the ring persists unchanged through many reactions. The groups of atoms attached to the ring, though, may come and go, and the reaction type responsible for replacing them is commonly ‘electrophilic substitution’. Whereas the missiles of Reaction 15 sniff out nuclei by responding to their positive electric charge shining through depleted regions of electron clouds, electrophiles, electron lovers, are missiles that do the opposite. They sniff out the denser regions of electron clouds by responding to their negative charge. Let’s suppose you want to make, for purposes you are perhaps unwilling to reveal, some TNT; the initials denote trinitrotoluene. You could start with the common material toluene, which is a benzene ring with a methyl group (–CH3) in place of one H atom, 2. Your task is to replace three of the remaining ring H atoms with nitro groups, –NO2, to achieve 3. And not just any of the H atoms: you need the molecule to have a symmetrical array of these groups because other arrangements are less stable and therefore dangerous. It is known that a mixture of concentrated nitric and sulfuric acids contains the species called the ‘nitronium ion’, NO2+, 4, and this is the reagent you will use. Before we watch the reaction itself, it is instructive to see what happens when concentrated sulfuric acid and nitric acid are mixed. If we stand, suitably protected, in the mixture, we see a sulfuric acid molecule, H2SO4, thrust a proton onto a neighbouring nitric acid molecule, HNO3. (Funnily enough, according to the discussion in Reaction 2, nitric ‘acid’ is now acting as a base, a proton acceptor! I warned you of strange fish in deep waters.) The initial outcome of this transfer is unstable; it spits out an H2O molecule which wanders off into the crowd. We see the result: the formation of a nitronium ion, the agent of nitration and the species that carries out the reaction for you.

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