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To study the corrosion behavior and discuss the corrosion mechanism of No. 20 carbon steel in water in the presence of sulfide ions.

The mass‐loss method, electrochemical tests and surface analysis were used to study the corrosion behavior and discuss the corrosion mechanism of No. 20 carbon steel in water in the presence of sulfide ions.

General corrosion occurred when No. 20 carbon steel was immersed in both test solutions (concentrated sample with S²⁻ added to 0.8 mg/L, and pure concentrated sample with no S²⁻ added). The presence of S²⁻ in test solutions accelerated the corrosion rate of No. 20 carbon steel.

In order to prevent No. 20 carbon steel in water with S²⁻ from corroding, S²⁻ must be removed.

It was found that the presence of S²⁻ in test solutions accelerated the corrosion rate of No. 20 carbon steel in this paper. Therefore, when water containing sulfide ions is used as the source of make‐up water and cooling water, S²⁻ in water must be removed to prevent the pipelines and facilities from corroding. This means the research results can offer theoretical guidelines for the prevention of pipelines and facilities in the power plant from corroding.

Some power plants in China that adopt reverse osmosis (RO) product water as their fresh water source face serious metal corrosion of their water distribution system. The corrosion process of carbon steel in RO product water is still not clear and there is no suitable anti‐corrosion method for the power plant to employ. The purpose of this paper is to study the corrosion behavior of carbon steel in RO product water, determine the factors leading to the high corrosion rate of carbon steel, and then suggest appropriate anti‐corrosion measures.

By measuring polarization curves and AC impedance values of the corrosion system and analyzing corrosion products using scanning electron microscopy (SEM), infrared spectroscopy (IR) and X‐ray diffraction (XRD), the corrosion behavior of Q235A carbon steel in the RO product water derived from seawater was studied.

The experimental results showed that the corrosion process of carbon steel in RO product water is controlled by the diffusion process of oxygen, and the corrosion products contain γ‐FeOOH, Fe₃O₄ and small amounts of α‐FeOOH. Although rust formed had a double layer structure, the outer rust layer, which contained γ‐FeOOH and a little α‐FeOOH, was thin. The inner rust layer, containing Fe₃O₄, was the main component of the rust layer. Due to the weak acidity of RO product water, γ‐FeOOH can be transformed to Fe₃O₄ very quickly and Fe₃O₄ will accumulate on the metal surface. Because of the electrical conductivity and fractured surface of the Fe₃O₄ layer, the corrosion product layer cannot inhibit the corrosion process by hindering the diffusion process of oxygen, and hence the corrosion rate of carbon steel is always high.

The paper describes the first systematic research to be carried out on the corrosion behavior of carbon steel in RO product water. It was found that the generation and accumulation of Fe₃O₄ on the metal surface was the primary reason leading to the high corrosion rate of carbon steel, and anti‐corrosion measures can be chosen following the following rules: deoxygenation, raising of the pH of the solution, or addition of corrosion inhibitors to the solution.

The inhibition mechanism and the relationship between the inhibition efficiency of para‐chlorobenzene nitriles on carbon steel in hydrochloric acid, and their molecular structure, were studied by microscopy and quantum chemistry calculations. The inhibition of carbon steel was achieved by chemisorption of the para‐chlorobenzene nitriles onto the surface of the carbon steel. The greater was the σ_N (absolute value) and the less the E_LUMO value, the greater was the inhibition efficiency.

The purpose of this paper is to present a study of corrosion inhibition of carbon steel in hydrochloric acid by some benzene nitriles using the quantum chemistry calculation.

The molecular structure and inhibition mechanism, and the relationship between inhibition efficiency of some benzene nitriles on carbon steel in the hydrochloric acid, were studied from a microcosmic viewpoint using the quantum chemistry calculation.

The calculation results showed that the inhibition efficiency of benzene nitriles on carbon steel in hydrochloric acid could be expressed by σ_N and E_LUMO, and the greater σ_N absolute value and the lesser the value of E_LUMO, then the greater the efficiency of the inhibitor. The regression equation for benzene nitriles is: η=2.665056−0.4447122E_LUMO−10.92817σ_N r=0.9953128.

The paper offers insights into the application of the quantum chemistry calculation.

This paper aims to study the corrosion behaviour of copper alloys HSn70‐1 + As and B30 in water with sulphide.

The mass‐loss method, electrochemical tests and surface analysis were used to study the corrosion behaviour of copper alloys HSn70‐1 + As and B30 in water with sulphide.

Dezincification corrosion occurred on HSn70‐1 + As both in water with or without sulphide, and sulphide in water accelerated corrosion, while for the copper alloy B30, the corrosion rates were very small both in water with or without sulphide, although corrosion was also accelerated by sulphide in water.

In order to prevent copper alloys HSn70‐1 + As and B30 in water with sulphide from corroding, S²⁻ must be removed.

It was found that sulphide in water accelerated the corrosion of copper alloys HSn70‐1 + As and B30 in this paper. Therefore, when water containing sulphide is used as the source of make‐up water and cooling water, S²⁻ in water must be removed to prevent the pipelines and facilities from corroding. This means that the research results can offer theoretical guidelines for the prevention of pipelines and facilities in the power plant from corroding.

This paper aims to describe a solution for cyclonic flue dust recycling based on the example of ferrochromium producers in Kazakhstan. It includes environmental improvement, which can be assessed in detail based on LCA after the development of a feasibility study of such a proposal.

Three pyrometallurgical recycling approaches should be achieved. The first approach is reduction smelting of fine waste in a direct current arc furnace without preliminary agglomeration. The second is reduction smelting of agglomerated waste in a submerged arc furnace, and the third is processing of agglomerated waste with liquid cast iron. The last approach facilitates the reactions of metal oxide reduction by carbon and silicon from the iron with a corresponding decrease in energy and auxiliary material consumption.

Valuable material can be produced from ferrochromium dust waste using environmentally friendly technology, including electric furnaces that can operate in SAF regimes and a simple plasma high‐power DC reactor operating under a neutral or reducing atmosphere. Finally, the investigation of waste recycling has developed a novel approach that facilitates metal oxide reduction and provides low energy and auxiliary materials consumption.

Research into the treatment of flue dust generated in the ferrochromium industry is needed to solve environmental problems not only in Kazakhstan but also in all ferrochromium plants in the world.

The three proposed pyrometallurgical recycling approaches should be achieved on a large scale.