On the problem of control over the primary grinding mill ball charging

Considering the fact that the costs related to grinding balls and electric power account for a significant share of operational costs incurred by concentrator plants, this paper highlights the relevance of using an optimized ball charge. The paper considers a conventional approach to ball charging, which involves doing calculations on the basis of a given throughput. The latter serves as a parameter for the specific ball consumption rate approval procedure. At the same time, no consideration is given for the ball wear rate as a parameter defining the grinding performance. It is noted that the ball charge dynamics can be analyzed based on the noise produced by the mill, or the vibroacoustic parameters of the mill. The paper examines some vibro-acoustic ball charge analysis techniques utilized by both domestic and international service providers. It is noted that in all these cases the technique uses just one physical parameter, which is not enough to monitor the total mill load. The VAZM-1M analyzer developed by Soyuztsvetmetavtomatika JSC analyzes and calculates an integral amplitude of the mill vibro-acoustic field. This ensures that all components of the grinding process are taken into account. The paper takes a detailed view of the findings obtained upon analysis of the primary grinding mill ball charge. The work was carried out at the Erdenet concentrator plant as part of contractual scope. A number of different ball charge options was considered, and is it noted that none of the options can resolve this problem completely. The authors describe a possibility to monitor the mill process load with the help of the VAZM-1M analyzer. The authors also analyzed the experiments that aimed at identifying the grinding parameters governed by the mill ball charge. It is shown that the VAZM-1M analyzer gives adequate readings of any ball charge deviations. The mill spectrum registered by the VAZM-1M analyzer contains a resonance peak, which is believed to correlate as a small mill ball charge spectrum. In this regard, a plan of further research was drafted that relies on the use of the VAZM-1M analyzer. The aim is to identify an exact frequency band that would adequately correlate with the mill ball charge.

Study on Quantitative Analysis of Carbon and Nitrogen in Stoichiometric θ-Fe3C and γ′-Fe4N by Atom Probe Tomography

The quantitative analysis performance of carbon and nitrogen was investigated using stoichiometric θ-Fe3C (25 at% C) and γ′-Fe4N (~20 at% N) precipitates in pulsed voltage and pulsed laser atom probes. The dependencies of specimen temperature, pulse fraction, and laser pulse energy on the apparent concentrations of carbon and nitrogen were measured. Good coincidence with 25 at% carbon concentration in θ-Fe3C was obtained for the pulsed voltage atom probe by considering the mean number of carbon atoms per ion at 24 Da and the detection loss of iron, while better coincidence was obtained for the pulsed laser atom probe by considering only the mean number of carbon at 24 Da. On the other hand, a lack of nitrogen concentration in γ′-Fe4N was observed for the two atom probes. In particular, the pulsed laser atom probe showed a significant lack of nitrogen concentration. This implies that a large amount of 14N2+ was obscured by the main iron peak of 56Fe2+ at 28 Da in the mass-to-charge spectrum. Regarding preferential evaporation or retention, carbon in θ-Fe3C exhibited little of either, but nitrogen in γ′-Fe4N exhibited definite preferential retention. This result can be explained by the large difference in ionization energy between carbon and nitrogen.

Probing spin correlations using angle-resolved photoemission in a coupled metallic/Mott insulator system

A nearly free electron metal and a Mott insulating state can be thought of as opposite ends of the spectrum of possibilities for the motion of electrons in a solid. Understanding their interaction lies at the heart of the correlated electron problem. In the magnetic oxide metal PdCrO2, nearly free and Mott-localized electrons exist in alternating layers, forming natural heterostructures. Using angle-resolved photoemission spectroscopy, quantitatively supported by a strong coupling analysis, we show that the coupling between these layers leads to an “intertwined” excitation that is a convolution of the charge spectrum of the metallic layer and the spin susceptibility of the Mott layer. Our findings establish PdCrO2 as a model system in which to probe Kondo lattice physics and also open new routes to use the a priori nonmagnetic probe of photoemission to gain insights into the spin susceptibility of correlated electron materials.

The concept of electric charge and the hypothesis of magnetic poles

We examine a generic field theory in which the field particle has two couplings. It is of particular interest when these are the electroweak, [Formula: see text], and the hypothetical magnetoweak, [Formula: see text]. The new field operators are obtained by replacing the field operators [Formula: see text] of the Standard Model or of similar models by [Formula: see text] where [Formula: see text] is an element of the [Formula: see text]-dimensional representation of the SLq(2) algebra, which is also the knot algebra. The new field is assumed to exist in two phases distinguished by two values of [Formula: see text]: [Formula: see text] and [Formula: see text] which label the electroweak and magnetoweak phases, respectively. We assume that the observed leptons and quarks are mainly composed of [Formula: see text]-preons and are in agreement with the observed charge spectrum of leptons and quarks. It is now proposed that there is also a [Formula: see text]-phase where [Formula: see text]-leptons and [Formula: see text]-quarks are composed of mainly [Formula: see text]-preons. It is assumed that the [Formula: see text]-charge is very large compared to the [Formula: see text]-charge and the mass of the [Formula: see text]-charged particle is even larger since the mass of all of these particles is partially determined by the eigenvalues of [Formula: see text], a polynomial in [Formula: see text], that multiplies the Higgs mass term and where [Formula: see text] Since these values of [Formula: see text] indicate that particles in the [Formula: see text]-phase are much more massive, they should be harder to produce or to observe. Since the remote parts of the universe are at increasingly higher temperatures, magnetic poles are perhaps most likely to be found in deep probes of space as well as in high energy accelerators. The section entitled “Introduction” was added only after it was generally realized that the birth of the present universe was probably due to a nuclear explosion.

Single-Ion Deconvolution of Mass Peak Overlaps for Atom Probe Microscopy

Due to the intrinsic evaporation properties of the material studied, insufficient mass-resolving power and lack of knowledge of the kinetic energy of incident ions, peaks in the atom probe mass-to-charge spectrum can overlap and result in incorrect composition measurements. Contributions to these peak overlaps can be deconvoluted globally, by simply examining adjacent peaks combined with knowledge of natural isotopic abundances. However, this strategy does not account for the fact that the relative contributions to this convoluted signal can often vary significantly in different regions of the analysis volume; e.g., across interfaces and within clusters. Some progress has been made with spatially localized deconvolution in cases where the discrete microstructural regions can be easily identified within the reconstruction, but this means no further point cloud analyses are possible. Hence, we present an ion-by-ion methodology where the identity of each ion, normally obscured by peak overlap, is resolved by examining the isotopic abundance of their immediate surroundings. The resulting peak-deconvoluted data are a point cloud and can be analyzed with any existing tools. We present two detailed case studies and discussion of the limitations of this new technique.