Application of Magnetic and Ultrasonic Methods for Determining Parameters of Ferromagnetic Components in Iron Ore Slurry Flows

The article considers the method for controlling the ferromagnetic component content in slurry flow by ultrasonic and magnetic measurements. One of the basic factors determining the efficiency of magnetic separators at iron ore concentration plants is the quality of distribution of the ground ore into the product containing the ferromagnetic component and the waste rock. Due to the fact that in most cases, magnetic separators extract minerals with strongly magnetic properties, it is essential to find the magnetic component content in the input ore and products of its distribution in order to improve control over the technological process. Currently, low accuracy and reliability make existing means of operative control over the ferromagnetic component content in the slurry flow inefficient. Density of slurry is one of the primary disturbing factors affecting the accuracy of measurements, and this fact determines the necessity of measuring this parameter while controlling the ferromagnetic component content. Combined methods of measurements are a promising trend in designing sensors of useful component content in the slurry flow. The article describes the method for controlling the ferromagnetic component content in slurry flow by ultrasonic and magnetic measurements.

Magnetic modes compatible with the symmetry of crystals

A classification of magnetic point groups is presented which gives an answer to the question: which magnetic groups can describe a given magnetic mode? There are 32 categories of magnetic point groups which describe 64 unique magnetic modes: 16 with a ferromagnetic component and 48 without. This classification focused on magnetic modes is helpful for finding the magnetic space group which can describe the magnetic symmetry of the material.

Borehole logging based on ultrasonic measurements

The coefficient of ultrasound attenuation is noted for sufficient sensitivity to provide high-quality characteristics of rocks. Efficiency of transforming electromagnetic signals into elastic oscillations of the ferromagnetic rock and backward depends on magnetic permeability of the rock, i.e. the content of the ferromagnetic component. The suggested method enables receiving additional data on concentration and structure of the ferromagnetic component distributed in the rock. To use the method one does not need either borehole liquid or any specific devices to introduce elastic oscillations into the rock, this fact facilitating its extensive application.

Method for Manufacturing of Fiber-Concrete Mixture for Fencing Structure Blocks

The authors offered a method for manufacturing concrete mixture with preliminary mixing of bonding material, modifying agent and basalt fibers in AC electromagnetic field using steel fiber as ferromagnetic component. The obtained fiber concrete was used for fencing with improved thermal characteristics.

Large linear magnetoelectric effect and field-induced ferromagnetism and ferroelectricity in DyCrO4

All the magnetoelectric properties of scheelite-type DyCrO4 are characterized by temperature- and field-dependent magnetization, specific heat, permittivity, electric polarization, and neutron diffraction measurements. Upon application of a magnetic field within ±3 T, the nonpolar collinear antiferromagnetic structure leads to a large linear magnetoelectric effect with a considerable coupling coefficient. An applied electric field can induce the converse linear magnetoelectric effect, realizing magnetic field control of ferroelectricity and electric field control of magnetism. Furthermore, a higher magnetic field (>3 T) can cause a metamagnetic transition from the initially collinear antiferromagnetic structure to a canted structure, generating a large ferromagnetic magnetization up to 7.0 μB f.u.−1. Moreover, the new spin structure can break the space inversion symmetry, yielding ferroelectric polarization, which leads to coupling of ferromagnetism and ferroelectricity with a large ferromagnetic component.

Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

High velocity impacts produce melts that solidify as ejected or in-situ glasses. We provide a review of their peculiar magnetic properties, as well as a new detailed study of four glasses from Siberia: El’gygytgyn, Popigai, urengoites, and South-Ural glass (on a total of 24 different craters or strewn-fields). Two types of behavior appear: 1) purely paramagnetic with ferromagnetic impurities at most of the order of 10 ppm; this corresponds to the five tektite strewn-fields (including the new one from Belize), urengoites, and Darwin glass. Oxidation state, based in particular on X-ray spectroscopy, is mostly restricted to Fe2+; 2) variable and up to strong ferromagnetic component, up to the 1 wt % range, mostly due to substituted magnetite often in superparamagnetic state. Accordingly, bulk oxidation state is intermediate between Fe2+ and Fe3+, although metallic iron, hematite, and pyrrhotite are sometimes encountered. Various applications of these magnetic properties are reviewed in the field of paleomagnetism, magnetic anomalies, recognition of glass origin, and formation processes.