System for the Measurement of the Copper Percentage in White Metal in a Smelting Furnace

Abstract

Provided is a system to measure the percentage of copper concentrate in the melting stage in-line and in real-time, it consists of at least four (1) electrodes inserted aligned through the refractory wall (2) of a smelting furnace, so that one end of each of the electrodes (1) remains on the outside of the furnace and the other end is inserted in the middle where the reaction occurs; i.e., inserted into the smelting bath, with these electrodes (1) connected to a signal amplifier which in turn is connected to signal generator, in which said power generator sends a replicated signal from the signal generator, sending the current-increased signals for charges with resistances of less than 0.1 ohm, and with bandwidths of 3 MHz, in which the power amplification sends the power signal to the electrodes (1) at the ends of the alignment so that the electrodes (1) that remain in the center receive the resistivity reading once the signal has been sent.

Claims

1. System to measure the percentage of copper concentrate in the melting stage in-line and in real-time, which allows the increase of the treatment capacity of concentrates, the reduction of slag reprocessing and the efficient use of the circulating element, all of which translates into reduced operational costs, CHARACTERIZED because it consists of at least four (1) electrodes inserted aligned through the refractory wall (2) of a smelting furnace, so that one end of each of the electrodes (1) remains on the outside of the furnace and the other end is inserted in the middle where the reaction occurs; i.e., inserted into the smelting bath, with these electrodes (1) connected to a signal amplifier which in turn is connected to signal generator, in which said power generator sends a replicated signal from the signal generator, sending the current-increased signals for charges with resistances of less than 0.1 ohm, and with bandwidths of 3 MHz, in which the power amplification sends the power signal to the electrodes (1) at the ends of the alignment so that the electrodes (1) that remain in the center receive the resistivity reading once the signal has been sent.

2. System to measure the percentage of copper concentrate in the melting stage in-line and real-time, in accordance with claim 1 is CHARACTERIZED because said electrodes are formed of steel refractory bars.

3. System to measure the percentage of copper concentrate in the melting stage in-line and real-time, in accordance with claim 1 is CHARACTERIZED because the signal generator is a device that generated different signal patterns that allow the behavior of the molten material to be analyzed, depending on the responses of the signals measured, both in terms of amplitude, current, lag, frequency runs, quadrature, resonance, attenuation and/or voltage increase over time.

4. System to measure the percentage of copper concentrate in the melting stage in-line and real-time, in accordance with claim 1 is CHARACTERIZED because it is also understood that these electrodes (1) are inserted aligned through the wall of the slag head (3) of a melting converter.

5. System to measure the percentage of copper concentrate in the melting stage in-line and real-time, in accordance with claim 1 is CHARACTERIZED because it is also understood that these electrodes (1) are inserted aligned through the wall of the white metal head (4) of a melting converter.

6. System to measure the percentage of copper concentrate in the melting stage in-line and real-time, in accordance with claims 1, 4 and 5 is CHARACTERIZED because the electrodes (1) are enclosed on the outside of the converter (5).

7. System to measure the percentage of copper concentrate in the melting stage in-line and real-time, in accordance with claim 1 is CHARACTERIZED because the electrodes that remain in the center of the alignment are connected to a data processor that interprets the resistivity reading measured by these electrodes as a percentage of copper present in the smelting bath in the melting furnace.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0010] FIGS. 1 and 2: show an illustration of how the electrodes are installed on the refractory wall of a casting furnace.

[0011] FIGS. 3 and 4: show an image of the electrodes installed in the slag head of a Lieutenant converter.

[0012] FIGS. 5 and 6: show an image of the electrodes installed in the white metal cylinder head of a Lieutenant converter.

[0013] FIG. 7: shows a cross-section linear resistor A and L-length connected to a DC voltage source to explain Ohms law.

[0014] FIG. 8: shows a graph illustrating the electrical resistivity depending on the temperature for copper without considering volume correction.

[0015] FIG. 9: shows a graph of the volume expansion quotient based on the temperature for copper.

[0016] FIG. 10: shows a graph of electrical resistivity based on the temperature for copper, considering volume correction.

[0017] FIG. 11: shows a graph of electrical conductivity based on the temperature for copper without considering volume correction.

[0018] FIG. 12: shows a graph of electrical conductivity based on the temperature for copper, with volume correction.

DETAILED DESCRIPTION OF THE INVENTION

[0019] In order to measure the copper concentration continuously in liquid phases at temperatures greater than 1200 [ C.], the background of the general behavior of electrical conductivity and resistivity in terms of temperature is considered as a theoretical base.

[0020] In particular, depending on the experimental references, the differences in resistivity and electrical conductivity are obtained based on temperature. In terms of the theory, the conductivity of a material changes drastically when the phase changes because the charge transportation mechanism and its interaction with the constituent particles of the material changes its nature. In the case of a solid material, the theory refers to phonons, which are arrangements of energy that travel through the crystalline network and interact with the charge carriers, obstructing their path, implying a change of conductivity at macroscopic level. In the case of liquid phases, the model refers to ionic solutions, in which the electrical charges interact with each other by Coulomb force, where the temperature randomly influences the velocity of the particles present in the solution. For example, electrical conductivity in a solid-state material is of the order of 910.sup.7 [1/Ohmm], whereas in a liquid state, it is 410.sup.7 [1/Ohmm].

[0021] The electromagnetic constituent parameters of a material medium are its electrical permittivity , magnetic permeability and conductivity . It is said that a material is homogeneous or uniform if its constitutive parameters do not vary from one point to another and in turn is isotropic, if its constitutive parameters are independent from the direction. There are a lot of materials that exhibit isotropic properties; however, not all crystalline solids, or liquids for that matter, possess this distinctive feature.

[0022] Electrical conductivity easily measures how electrons can travel through the material influenced by an external electric field. Materials are classified as electric conductors (metals) or dielectric (insulating) depending on the magnitudes of their conductivity.

[0023] A conductor has a large number of electrons adhered weakly to the outermost layers of atoms. Without an external electrical field, these free electrons move in random directions at variable speeds. Its random movement produces a zero average current through the conductor. However, when applying an external electrical field, the electrons migrate from one atom to the next along a direction contrary to that of the external field. Its movement, which is characterized by an average velocity, known as electron flow velocity, causes a conduction current.

[0024] In a dielectric material, the electrons are strongly adhered to the atoms, which implies that it is difficult to detach them under the application of an electric field. Consequently, no current flows through the material.

[0025] A perfect dielectric is a material with a of almost zero, and in contrast, a perfect conductor is a material with a very large . The electrical conductivity of most metals is within the range of 10.sup.6 to 10.sup.7 [1/Ohmm], compared to 10.sup.10 to 10.sup.7 of good insulators (See Table 1).

TABLE-US-00001 TABLE 1 Electrical Conductivity of some common materials at 20 C. (and low frequency) Material Conductivity [1/ohm m] Conductors Silver 6.2 10.sup.7 Copper 5.8 10.sup.7 Gold 4.1 10.sup.7 Aluminum 3.5 10.sup.7 Iron 10.sup.7.sup. Mercury 10.sup.6.sup. Coal 3 10.sup.4 Semiconductor Pure Germanium 2.2 Pure Silicon .sup.4.4 10.sup.4 Insulators Glass 10.sup.12 Paraffin 10.sup.15 Mica 10.sup.15 Fused Quartz 10.sup.17

[0026] The materials with electrical conductivity between that of conductors and insulators are known as semiconductors.

[0027] The electrical conductivity of a material depends on a number of factors, including temperature and the presence of impurities. In general in metals, conductivity decreases with the increase of the temperature and on the other hand, at very low temperatures close absolute zero, some conductors become superconductors because their conductivity levels become very high.

[0028] A perfect conductor is an equipotential medium, which means that the electrical potential is the same at all points of the conductor. This property is derived from that the difference between two points of the conductor is equal by definition, equal to the total of the field line between two points. However, the field is equal to zero in all parts of the conductor, so the voltage difference is zero. However, the fact that the conductor is an equipotential medium does not necessarily imply that the difference of potential between the conductor any other conductor is zero. Each conductor is an equipotential medium, but the presence of different charge distributions on its surfaces can generate a difference in potential between them.

[0029] The Ohm law is used on this occasion to introduce another important term that is more usable in references: resistivity:

[00001]$\begin{array}{cc}\stackrel{.fwdarw.}{J}=\stackrel{.fwdarw.}{E}& \left(1\right)\end{array}$ [0030] {right arrow over (J)}: Current density vector, [0031] : Electrical Conductivity. [0032] {right arrow over (E)}: Electric field vector.

[0033] FIG. 7 shows a conductor length L, resistance R, and cross-section A. The conductor axis is oriented along the x-axis and extends between the X-Points.sub.1 and X.sub.2, with L=X.sub.2X.sub.1.

[0034] A voltage V applied between the terminals of the conductor establishes an electric field:

[00002]$\stackrel{.fwdarw.}{E}=\mathrm{Ex}\hat{i}$

[0035] The E-direction is the highest potential point (point 1 in FIG. 7) to the lowest potential point (point 2 FIG. 7).

[0036] The relationship between the voltage and the electrical field component in X is obtained as follows:

[00003]$\begin{array}{cc}V=V_2-V_1=-\underset{x_2}{\overset{x_1}{}}\stackrel{.fwdarw.}{E}.Math.d\stackrel{.fwdarw.}{l}=E_{x}l& \left(2\right)\end{array}$

[0037] The current flowing through section A of the conductor is the total of the current density on the surface:

[00004]$\begin{array}{cc}I=\underset{A}{}\stackrel{.fwdarw.}{J}.Math.d\stackrel{.fwdarw.}{S}=\underset{A}{}.Math.\stackrel{.fwdarw.}{E}.Math.d\stackrel{.fwdarw.}{S}=E_x\stackrel{\_}{A}& \left(3\right)\end{array}$

[0038] On the other hand, the best known relationship of Ohm Law and (2) and (3) is:

[00005]$\begin{array}{cc}R=\frac{l}{A}=\frac{l}{A}& \left(4\right)\end{array}$

[0039] Where is another important parameter, known as electrical resistivity, and is the inverse of conductivity. The latter is the most studied in temperature-based behavior. In this manner, by establishing its shape, the electrical conductivity be indirectly established.

[0040] According to the theories, electrical resistivity and therefore the resistance in a conductor depend on the temperature, and in many cases, it can be assumed that resistivity depends linearly.

[0041] In a temperature range not too large, the resistivity of a metal can be represented approximately by the following equation:

[00006]$\begin{array}{cc}{}_T={}_0.Math.\left[1+.Math.\left(T-T_0\right)\right]& \left(5\right)\end{array}$

[0042] Where .sub.0 is the resistivity at a reference temperature T.sub.0 (usually taken as at 20 C. or the ambient temperature) and .sub.T resistivity at a temperature T. The factor is known as the resistivity temperature coefficient. Table 2 show the representative values of this coefficient.

TABLE-US-00002 TABLE 2 Resistivity temperature coefficients. Material [ C..sup.1] Aluminum 0.0039 Carbon 0.0005 Copper (recognized commercial) 0.00393 Constantan (Cu 60, Ni 40) 0.000002 Iron 0.0050 Brass 0.0020 Manganin (Cu 84, Mn 12, Ni 4) 0.000000 Mercury 0.00088 Nichrome 0.0004 Silver 0.0038 Lead 0.0043 Tungsten 0.0045

[0043] It may be the case that electrical resistivity varies non-linearly with temperature, which implies that it is advisable to express this property in terms of potency series:

[00007]$\begin{array}{cc}={}_0\left(1+\underset{i}{.Math.}{{}_i\left(T\right)}^i\right)& \left(6\right)\end{array}$

[0044] Of all the known references and also considering that copper is a metal, electrical resistivity has an increasing linear behavior with temperature. In addition, when it reaches its melting point, its electrical resistivity increases, particularly for copper, in the increase is approximately double, as basically the volume changes inside the metal.

[0045] For example, FIG. 8 shows the electrical resistivity graph for copper based on temperature, without correction for volumetric change, using the equation (5) with T.sub.0=293 K and .sub.0=1.7210.sup.8 [Ohmm].

[0046] The expansion of volume is known to derive from thermodynamics depending on the change in length, as an extension of the linear expansion of solids subjected to temperature (in classical thermodynamics):

[00008]$\begin{array}{cc}\frac{V}{V_0}=3.Math.\left(\frac{L}{l_0}\right)+3{\left(\frac{L}{l_0}\right)}^2+{\left(\frac{L}{l_0}\right)}^3& \left(7\right)\end{array}$

[0047] Then the graph of volume ratio variation based on temperature can be obtained, as observed in FIG. 9. From this graph, it can be observed that at the melting point1356 [K] or 1083 [ C.], there is a change in the quotient from 1.037 to 1.095. Since electrical resistivity depends implicitly on length variables, it is also affected by the change in volume. In practice, this means that the current must be extended in a greater space; therefore, the body or surface becomes more resistive.

[0048] By making the respective transformations, the graph in FIG. 10 that illustrates the resistivity corrected according to the temperature with the following equations that parameterize the functions:

[00009]${}_{\mathrm{corr}}\left(T\right)=-0.02861+9.98873{10}^{-5}\begin{array}{cc}T& 1100K<T<1356K\end{array}{}_{\mathrm{corr}}\left(T\right)=0.11031+7.83066{10}^{-5}\begin{array}{cc}T& 1356K<T<1900K\end{array}$

[0049] Based on the foregoing, it is known that electrical resistivity is the multiplicative inverse of electrical conductivity, and therefore, in practice the behavior of electrical conductivity is:

[00010]$\begin{array}{cc}{}_T=\frac{1}{{}_0.Math.\left[1+.Math.\left(T-T_0\right)\right]}& \left(8\right)\end{array}$

[0050] Based on temperature, the graph of this equation 8 would be as shown in FIG. 11. According to the foregoing, the correction of the volume in the transformation from solid to liquid state modifies the electrical resistivity values depending on the temperature (since they do not modify the form), implies that given the increase in volume, a fluid is more resistant to the passage of current. On the contrary, the electrical conductivity has an inverse behavior: the greater the volume of the body or bath to be investigated, it is less conductive; therefore, the decrease is greater due to the high temperatures.

[0051] As can be seen in the graph in FIG. 12, the value of the electrical conductivity of copper passing the melting point decreases from 910.sup.7 to 410.sup.7 [1/Ohmm] approximately, which implies that, in practice, the values should not be greater than 910.sup.7 (values assignable to the solid state).

[0052] Considering the aforementioned concepts, the system used to measure the percentage of copper in a casting bath considers that the higher the copper concentrations are in a molten metal bath (e.g., white metal), its electrical conductivity is greater. In practice, this should be consistent insofar that if a white metal sample with a 72.8% copper content should show a conductivity below 73.8.

[0053] From the point of view of measurement, the system allows frequencies to be varied frequencies and samples of white metal to be compared with different copper contents in a molten state its alternating current electrical conductivity to be measured using 4-wire sensing (Kelvin) techniques. This technique eliminates the need for wiring and contact potentials. It is very useful to measure very low-value resistances using special geophysical prospecting applications. The technique was originally developed by Lord Kelvin, later perfected by Frank Wenner at the beginning of the 20th century, who used it to measure the resistivity of soil samples. In geophysics, this technique is known as Wenner Method. It is most common to measure a resistance of intermediate values (tenths of [Ohm] to a few mOhm) with two points using a multimeter.

[0054] Thus, the system of the invention consists of at least four aligned electrodes (1) that are inserted through the refractory wall (2) of a smelting furnace, so that one end of each of the electrodes (1) remains on the outside of the furnace and the other end is inserted in the middle where the casting reaction occurs; i.e., inserted in the smelting bath.

[0055] The electrodes (1) are connected to a signal amplifier, which is an amplifier that receives a signal from a signal generator connected to the amplifier and sends them to the electrodes (1). Strictly speaking, the amplified signal consists of sending a low-voltage current, in the order of 6 V, but with a high current, in the order of the 30 A, in such a manner so as to interfere as little as possible with the resistivity of the liquid copper in the bath and thus measure the changes observed as its state changes during the reaction process.

[0056] Specifically, the amplified signal consists of a signal increased in current for charges with resistances below 0.1 ohm, and with bandwidths of 3 MHz, in which the power amplification sends the power signal to the electrodes (1) arranged on the ends of the alignment, so that the electrodes (1) arranged in the center receive the resistivity reading once the signal has been sent. To do so, the electrodes arranged in the center of the alignment are connected to a data processor that interprets the resistivity reading of these electrodes as a percentage of copper present in the smelting bath in the melting furnace.

[0057] In a preferred mode of execution, the electrodes (1) are inserted aligned through the slag head wall (3) of a melting converter and in another preferred mode the electrodes (1) are inserted aligned through the head wall of white metal (4) of a melting converter. In both cases, the electrodes (1) are covered by an enclosure on the outside of the converter (5).

[0058] The electrodes (1) are formed or steel refractory bars, which have conditions suitable for balancing resistivity. The resistance increase of steel refractory bars is very slow due to aging: they can increase with a ratio of approximately 5-6% for every 1,000 hours of continuous operation at 1,400 C. and a ratio of 3% for every 1,000 hours of continuous operation at 1,000 C.