Effect of 2CaO·SiO2 particles addition on dephosphorization behavior

The effect of the addition of 2CaO·SiO2 solid particles on dephosphorization behavior in carbon-saturated hot metal was investigated. The research results showed that the addition of 2CaO·SiO2 particles have little influence on desilication and demanganization, and the removal of [Si] and [Mn] occurred in the first 5 min with different conditions where the contents of 2CaO·SiO2 particles addition for the conditions 1, 2, 3, 4, and 5 are 0, 2.2, 6.4, 8.6, and 13.0 g, respectively. The final dephosphorization ratios for the conditions 1, 2, 3, 4, and 5 are 61.2%, 66.9%, 79.6%, 63.0%, and 78.1%, respectively. The dephosphorization ratio decreases with the increase of 2CaO·SiO2 particles in the first 3 min. The reason for this is that the dephosphorization process between hot metal and slag containing C2S phase consisted of two stages: Stage 1, [P] transfers from hot metal to liquid slag and Stage 2, the dephosphorization production (3CaO·P2O5) in liquid slag reacts with 2CaO·SiO2 to form C2S–C3P solid solution. The increase of 2CaO·SiO2 particles increases the viscosity of slag and weakens the dephosphorization ability of the stage 1. The SEM and XRD analyses show that the phase of dephosphorization slag with the addition of different 2CaO·SiO2 particles is composed of white RO phase, complex liquid silicate phase, and black solid phase (C2S or C2S–C3P). Because the contents of C2S–C3P and 2CaO·SiO2 in slag and the dephosphorization ability of the two stages are different, the dephosphorization ability with different conditions is different.

Foliar Application of Liquid-Silicate Rock Fertilizer Reduced Pest and Disease Attacks and Improved Bean Production of Cocoa

Besides the lack of soil fertilization, the primary biotic stressor limiting the production of cocoa (Theobroma cacao L.) in Indonesia is pest and disease attacks (PDAs). As a part of the efforts to find out the appropriate solution for the farming constraints, a field trial was carried out for 14 months (2015 – 2016) in Genggelang - North Lombok Regency, Indonesia. The main objective of the experiment was to identify the effects of the use of locally-available materials, i.e., liquid-silicate rock fertilizer (LSRF), botanical pesticide (BP) of neem, and black ants (BA) of Doliccoderus thoracic, on PDAs, bean production, and polyphenol and lignin contents of cocoa pod shell. A randomized complete block design was laid out in three blocks, and the treatments were LSRF, LSRF+BP, LSRF+BA, BA, and control. Results reveal that the application of those materials reduced the intensity of pest and disease attacks (e.i., respectively, 6 - 24 % and 3 - 9 % lower than for that of the control), increased 18 – 119 % of bean production, and improved the polyphenol and lignin contents of pod shell. The highest increase (119 %) of bean production was due to the foliar application of LSRF. The positive effect of the treatments, especially the use of LSRF, associated with the improvement of the resistance of cocoa to PDAs and appropriate supply of plant-essential nutrients. Therefore, the foliar application of LSRF may be promoted as a proper method to improve the production of cocoa, especially of that grown on less fertile soils.

Fate of MgSiO3 melts at core–mantle boundary conditions

One key for understanding the stratification in the deep mantle lies in the determination of the density and structure of matter at high pressures, as well as the density contrast between solid and liquid silicate phases. Indeed, the density contrast is the main control on the entrainment or settlement of matter and is of fundamental importance for understanding the past and present dynamic behavior of the deepest part of the Earth’s mantle. Here, we adapted the X-ray absorption method to the small dimensions of the diamond anvil cell, enabling density measurements of amorphous materials to unprecedented conditions of pressure. Our density data for MgSiO3 glass up to 127 GPa are considerably higher than those previously derived from Brillouin spectroscopy but validate recent ab initio molecular dynamics simulations. A fourth-order Birch–Murnaghan equation of state reproduces our experimental data over the entire pressure regime of the mantle. At the core–mantle boundary (CMB) pressure, the density of MgSiO3 glass is 5.48 ± 0.18 g/cm3, which is only 1.6% lower than that of MgSiO3 bridgmanite at 5.57 g/cm3, i.e., they are the same within the uncertainty. Taking into account the partitioning of iron into the melt, we conclude that melts are denser than the surrounding solid phases in the lowermost mantle and that melts will be trapped above the CMB.

A study on transformation of some transition metal oxides in molten steelmaking slag to magnetically susceptible compounds

Sustainable development of steelmaking requires solving a number of environmental problems. Economically feasible and environmentally friendly recycling of slag wastes is of special concern. Research of the team representing National Metallurgical Academy of Ukraine, Royal Institute of Technology, Carnegie Mellon University and URS Corp revealed a possibility of the controlled phase transformations in the liquid silicate melts followed by formation of the magnetically susceptible compounds. This approach enables selective recovery of metal values from slag. In this paper, the results obtained and further research directions are discussed. A possibility to exploit physical properties of the transition metals, typical for the metallurgical slags (such as Fe, Mn, V and others), and corresponding specific properties of their compounds, such as non-stoichiometry, mixed valency, pseudomorphosis, thermodynamic stability etc, in production of value-added materials from slag wastes is discussed. The results of the studies of thermodynamics and kinetics of oxidation in slags followed by phase transformation with binary, ternary and complex oxides under various physicochemical conditions are discussed in the view of their application for production of the materials with predefined physical properties. Peculiarities of precipitation in slags with various basicities are analysed and demonstrate capacity of the proposed approach in the production of the material with a given structure and size - for example, nano-sized crystals with structure of spinel. The approaches towards industrial realization of the developed method are also discussed.

Viscosity model for fully liquid silicate melt

A model for estimating the viscosity of silicate melt as derived in our previous paper is extended to the system containing MgO, CaO, SrO, BaO, Li2O, Na2O, K2O, which can express the nonlinear variation of activation energy of viscosity with the composition. It is found that the optimized parameters of model which characterize the deforming ability of bonds around non-bridging oxygen decrease with increasing the bond strength of M-O bond expressed by I=2Q/RMz+ + rO2-)2 (where Q is the valence of cation M; r is the radius). It is pointed out that viscosity is not only determined by the bond strength, but also by the radius of cation which is defined as the size effect. The radius of cation plays paradox roles in the two factors: smaller radius leads to a stronger bond, thus a higher viscosity; while cations with smaller radius are easier to diffuse when neglecting the interaction force, thus a lower viscosity will be.