CN104316439A - Device and method for determining rheological properties of high-temperature metallurgy molten slag - Google Patents

Abstract

A device and method for measuring the rheological properties of pyrometallurgical slag, the device includes an electric heating furnace, a crucible, a rheometer and a temperature control system; the electric heating furnace is fixed on the lifting device, the crucible is fixed in the furnace tube, and the rheometer The hook is attached to the rotor, which is located inside the crucible. The method is: (1) break the slag sample into slag and place it in a crucible; (2) pass protective gas into the furnace tube and keep it in circulation; The temperature in the furnace tube is lowered, and the rheological properties of the slag are tested during the cooling process, and the analysis data is collected; (4) According to the corresponding shear stress at different shear rates measured by the rheometer, a slag rheological book is established Constructive equations to determine the rheological parameters of slag. The device and method of the invention can quickly and accurately test the rheological properties of high-temperature slag.

Description

A device and method for measuring rheological properties of pyrometallurgical slag

technical field

The invention belongs to the technical field of metallurgy, in particular to a device and method for measuring the rheological properties of high-temperature metallurgical slag.

Background technique

Pyrometallurgical slag is mainly a melt composed of oxides in metallurgical raw materials or oxides generated during the metallurgical process; high-temperature metallurgical slag plays an important role in the smelting process; high-temperature metallurgical slag is mainly composed of oxides, and its composition It is very similar to the liquid phase of the refractory material, and it can be considered that the liquid phase of the refractory material may play a similar role to the slag. In fact, once a certain amount of liquid phase exists at high temperature, the refractory oxide particles are wrapped by the liquid phase, and the liquid phase is not the refractory oxide that is in direct contact with the molten steel. Pyrometallurgical slag is a kind of high-temperature solution, and its structure is very complex, which has not been fully studied until now.

The pyrometallurgical process can produce various metallurgical slags according to different smelting methods and products, and the difference in the properties of the slag can directly affect the quality of the metallurgical process and various metallurgical products; Complex, so the theoretical research on pyrometallurgical slag progresses slowly.

It is generally believed that slag is a Newtonian fluid at higher temperatures, but it will show the characteristics of non-Newtonian fluid when there are gas and solid phase particles in the slag or a silicate network structure, especially the polymetallic symbiosis of mineral resources in my country. The characteristics of high-temperature metallurgical slag make the composition and structure of high-temperature metallurgical slag more complex and deviate far from Newtonian fluid, such as the titanium-containing blast furnace slag produced by blast furnace smelting of vanadium-titanium magnetite in my country. Long-term research and industrial practice have proved that if titanium in titanium-containing blast furnace slag exists only in the form of TiO ₂ or CaO·TiO ₂ , it will not cause great difficulties in blast furnace smelting. However, under high temperature and strong reducing conditions, part of the _TiO2 in the slag is reduced to TiC, TiN and its solid solution Ti(C,N) with high melting point. These titanium compounds are usually dispersed in the liquid state in the form of highly dispersed tiny solid particles. In the slag, a gas-solid-liquid three-phase complex system is formed, which causes a series of special problems such as the rapid thickening of the slag, poor fluidity, iron in the slag, and the formation of foamy slag. difficulty. At present, many theoretical studies have been carried out on the formation and evolution of titanium-containing blast furnace slag, but the understanding of its rheological characteristics and transformation laws is still vague and insufficient, and the relevant research lags behind the industrial production practice. In addition, the existing theoretical system of pyrometallurgical slag is basically based on homogeneous and Newtonian fluids, so it has great limitations; however, most of the actual pyrometallurgical slags are heterogeneous and non-Newtonian melts, so it is urgent to Introduce new theories and research ideas, choose correct research and testing methods, and systematically carry out research on the rheological properties and transformation laws of this type of melt.

In the early 1990s, Flemings first applied the theory of rheology to the solid-liquid two-phase non-Newtonian melt that appeared in the semi-solid processing of liquid metal, which explained the solidification process of liquid metal well, thus opening up people's application of rheology. It is a new way to solve many physical and chemical problems of heterogeneous non-Newtonian melts. The use of rheological methods to study the transformation process and law of homogeneous Newtonian slag to heterogeneous non-Newtonian slag is very beneficial to a comprehensive understanding of the rheological properties of pyrometallurgical slag, but unfortunately, research in this area is very limited. limited.

At present, the quasi-Newtonian fluid measurement method is mostly used for the rheological properties of high-temperature melts. This is a relative measurement method, that is, the melt with unknown fluid properties is treated as Newtonian fluid first, and the high-temperature rotational viscometer When the rotation speed is high, the viscosity η of the melt at this rotation speed can be measured. When the viscosity is measured by the rotation method, since the size of the crucible and the probe is determined, the shear rate D generated by the rotation motion is only a function of the rotation speed; according to different rotation speeds Find the corresponding shear rate, and then according to the viscosity η measured under the rotating speed, the shear stress τ can be obtained by the formula τ = η D ; according to the τ value during different D values, the τ - D curve of the fluid is made, That is, the rheological characteristic curve of the fluid, and then obtain the constitutive equation of the fluid; according to the form of the constitutive equation and the index n of D (n is the flow index) greater than 1, equal to 1 or less than 1, and then judge whether the fluid belongs to Newtonian fluid or Non-Newtonian fluid; however, this method has cumbersome steps, and the experimental error is not easy to control, and the accuracy of the calculated results is not high.

Contents of the invention

Aiming at the above-mentioned deficiencies existing in the measurement technology of the rheological properties of the pyrometallurgical slag, the present invention provides a device and method for measuring the rheological properties of the pyrometallurgical slag. During the cooling process, the slag samples are tested separately. According to the shear stress corresponding to the shear rate, the constitutive equation is established, and the constitutive equation of the slag is directly obtained according to the actual measurement results, which is convenient for analysis and judgment of the fluid type of the slag.

The device for measuring the rheological properties of pyrometallurgical slag of the present invention includes an electric heating furnace, a crucible, a rheometer and a temperature control system; the electric heating furnace is fixed on the lifting device, the crucible is fixed inside the furnace tube of the electric heating The hook of the instrument is connected to the rotor through the rotating rod, and the rotor is located inside the crucible; there is a gas channel at the bottom of the furnace tube, the thermocouple in the furnace tube is assembled with the temperature control system, and the heating element in the electric heating furnace is assembled with the temperature control system. Together, the rheometer is assembled with a computer, and the temperature control system is connected with the computer.

The furnace body of the above-mentioned electric heating furnace is provided with insulation material inside, and a cavity is provided inside the insulation material, and the lower part of the heating element is located in the cavity.

The top of the furnace tube of the above-mentioned electric heating furnace is provided with a through hole of the rotating rod, and there is a gap between the through hole of the rotating rod and the rotating rod; the bottom of the furnace tube is provided with a crucible seat, and the crucible is located on the crucible seat in the furnace tube, and the crucible is located on the insulation material. in the internal cavity.

The aforementioned thermocouples are inserted into the bottom of the furnace tube.

The gas channel at the bottom of the above-mentioned furnace tube communicates with the gas bottle through a pipeline.

The lifting device mentioned above is fixed on the supporting frame, and the supporting frame is also provided with a fixed platform on which the rheometer is fixed.

The material of the above-mentioned rotor is molybdenum.

The above-mentioned rotating rod is made of corundum.

The material of the above-mentioned crucible is graphite and the inner wall is provided with a lining, and the material of the lining is molybdenum.

The method for measuring the rheological properties of pyrometallurgical slag of the present invention is to adopt the above-mentioned device, and carry out according to the following steps:

1. Break the slag-like slag and place it in the crucible;

2. Introduce protective gas into the furnace tube and keep it in circulation; heat the slag sample to 1500±10°C through an electric heating furnace to form molten slag, and keep it warm for at least 1 hour;

3. The temperature in the furnace tube is controlled by the temperature control system to cool down. During the cooling process, the rheological properties of the slag are tested by the rheometer, and the data is collected and analyzed by the computer until the data exceeds the range of the rheometer;

4. According to the corresponding shear stress at different shear rates measured by the rheometer, establish the rheological constitutive equation of the slag, and determine the rheological characteristic parameters of the slag.

In the above step 3, the temperature range of the rheometer test is 1350~1500°C, and a measurement is performed every 25±1°C.

In the above method, when the rheological properties of the slag sample are tested by a rheometer, the shear rate of the rotor is 2.5~43.4s ^-1 .

The above constitutive equation adopts the Herschel-Bulkley model: τ=τ _y +kD ⁿ ; where τ is the shear stress in Pa; τ _y is the yield stress in Pa; k is the viscosity factor; D is the shear Speed, the unit is s ^-1 ; n is the flow index.

The above-mentioned protective gas is argon or nitrogen.

The above-mentioned rheometer is a low-temperature rheometer with an operating temperature of -100°C to 300°C.

The device and method of the invention can quickly and accurately test the rheological properties of high-temperature slag, and has high testing accuracy, low cost, simple operation, and can more comprehensively characterize the rheological properties of high-temperature metallurgical slag.

Description of drawings

Fig. 1 is the device structural representation of measuring pyrometallurgical slag rheological characteristic of the present invention; Among the figure, 1, computer, 2, temperature control system, 3, rheometer, 4, suspension hook, 5, rotating rod, 6, Fixed platform, 7, furnace tube, 8, furnace body, 9, heating element, 10, insulation material, 11, rotor; 12, crucible, 13, slag, 14, thermocouple, 15, bottom cover, 16, electric screw Lifting device, 17, support frame, 18, gas cylinder, 19, crucible seat;

Fig. 2 is TiO in the embodiment of the present invention ₁ The τ-D curve figure when content 15%;

Fig. 3 is TiO in the embodiment of the present invention 1 _The τ-D curve figure when content 20%;

Fig. 4 is TiO in the embodiment of the present invention 1 _The τ-D curve figure when content 25%;

Fig. 5 is TiO in the embodiment of the present invention 1 _The τ-D curve figure when content 30%;

Fig. 6 is TiO in the embodiment of the present invention 1 _The τ-D curve figure when content 35%;

Fig. 7 is the τ-D curve figure when TiC content 2% in the embodiment of the present invention 2;

Fig. 8 is the τ-D graph when TiC content is 4% in the embodiment of the present invention 2;

Fig. 9 is the τ-D curve diagram when TiC content is 6% in the embodiment of the present invention 2;

Fig. 10 is a τ-D curve diagram when the TiC content is 8% in Example 2 of the present invention.

Detailed ways

The rheometer model that adopts in the embodiment of the present invention is Brookfield DV-Ⅲ; The software supporting use is called Brookfield application software.

The temperature control system adopted in the embodiment of the present invention is an ADAM module.

The composition of the slag sample used in the examples of the present invention contains CaO 22~33%, SiO ₂ 20~30%, MgO 8%, Al ₂ O ₃ 14%, TiO ₂ 9~35%, TiC 2~8 by weight percentage. %.

The weight of the slag sample in the crucible in the embodiment of the present invention is 140g.

The heating body in the embodiment of the present invention is molybdenum disilicide; the electric heating furnace is molybdenum disilicide electric heating furnace

The insulation materials in the embodiment of the present invention are commercially available alumina refractory bricks and alumina hollow balls.

Application Brookfield application software software in the embodiment of the present invention, adopt Herschel-Bulkley model to carry out regression processing to experimental measurement data, and use castor oil (standard Newtonian fluid) to carry out calibration and process to experimental error; (for the yield stress τ _y in the regression equation , if the value is less than 0, it does not conform to the principle of energy conservation, and it is treated as 0; if it is greater than 0, it is necessary to compare the error of its influence on the viscosity factor whether it is ignored or not; ; choose castor oil (standard Newtonian fluid) calibration experiment at 17.5°C The maximum allowable deviation (7.67%) of τ _y in the regression equation, this value is used as the basis for judging whether to ignore τ _y in the regression equation; that is, the value of τ _y in the regression equation is less than or equal to 7.67% will be ignored; similarly, when the regression equation When the fluidity index n in is not 1, the maximum relative error σ (10.6%) of castor oil at 17.5°C is used as the basis for comparing whether n is 1; the relative error calculation formula is σ=|D ⁿ -D ^1.00 ⁄D ^1.00 |x100%, the D value is taken as the maximum shear rate value 43.4s ^-1 in each measurement experiment during calculation; if the σ value of the regression equation is less than the maximum relative error of the castor oil experiment of 10.6%, then the n value is corrected to 1, At this time, the constitutive equation is given by n=1).

Example 1

The device structure for measuring the rheological properties of pyrometallurgical slag is shown in Figure 1, including an electric heating furnace, a crucible 12, a rheometer 3, a temperature control system 2 and a computer 1;

The electric heating furnace is fixed on the electric screw lifting device 16. The electric heating furnace includes a furnace body 8 and the furnace tube 7 inside it, an insulating material 10 and a heating element 9. A cavity is arranged inside the insulating material 10, and the lower part of the heating element 9 is located at inside the cavity;

The crucible 12 is fixed inside the furnace tube 7, the hook 4 of the rheometer 3 is connected to the rotating rod 5, the bottom of the rotating rod 5 is connected to the rotor 11, and the rotor 11 is located inside the crucible 12;

The bottom cover 15 at the bottom of the furnace tube 7 is provided with a gas channel, the thermocouple 14 in the furnace tube 7 is assembled with the temperature control system 2, the heating element 9 in the electric heating furnace is assembled with the temperature control system 2, and the rheology The instrument 3 is assembled with the computer 1, and the temperature control system 2 is connected with the computer 1;

The top of the furnace tube 7 is provided with a through hole of the rotating rod, and there is a gap between the through hole of the rotating rod and the rotating rod 5; Located in the cavity inside the thermal insulation material 10;

The thermocouple 14 is inserted into the bottom of the furnace tube 7 through the bottom cover 15;

The gas passage communicates with the gas cylinder 18 through a pipeline;

The electric screw lifting device 16 is fixed on the support frame 17, the support frame 17 is also provided with a fixed platform 6, and the rheometer 3 is fixed on the fixed platform 6;

The material of the rotor is molybdenum, the shape is spindle-shaped, and the material of the rotating rod is corundum; the material of the crucible is graphite and the inner wall is lined with molybdenum;

Using the above-mentioned device, the rheological property test method is carried out according to the following steps:

1. Break the slag-like slag and place it in the crucible;

2. Introduce protective gas into the furnace tube and keep it in circulation; the protective gas is argon or nitrogen; heat the slag sample to 1500±10°C through an electric heating furnace to form molten slag, and keep it warm for 1h;

3. The temperature in the furnace tube is controlled by the temperature control system to cool down. During the cooling process, the rheological properties of the slag are tested by the rheometer, and the data is collected and analyzed by the computer until the data exceeds the range of the rheometer;

4. According to the corresponding shear stress at different shear rates measured by the rheometer, the rheological constitutive equation of the slag is established to determine the rheological characteristic parameters of the slag;

The temperature range of the rheometer test is 1350~1500°C, and the measurement is carried out every 25±1°C; when the rheological properties of the slag sample are tested by the rheometer, the shear rate of the rotor is 2.5~43.4s ^-1 ; The Herschel-Bulkley model is adopted for the construction equation: τ=τ _y +kD ⁿ ; where τ is the shear stress in Pa; τ _y is the yield stress in Pa; k is the viscosity factor; D is the shear rate in Pa is s ^-1 ; n is the flow index;

The composition of the slag sample used is shown in Table 1;

Table 1 (wt%)

No. CaO SiO ₂ MgO Al ₂ O ₃ TiO ₂ ∑ Alkalinity (CaO/SiO ₂ ) 1 33 30 8 14 15 100 1.10 2 30.38 27.62 8 14 20 100 1.10 3 27.76 25.24 8 14 25 100 1.10 4 25.14 22.86 8 14 30 100 1.10 5 22.52 20.48 8 14 35 100 1.10

Taking No.1 experiment as an example, the composition of the slag sample contains 33% CaO, 30% SiO ₂ , 8% MgO, 14% Al ₂ O ₃ , and 15% TiO ₂ by weight percentage; Assuming τ _y ≠ 0, the constitutive equation is τ=-1.1950+2.8815D ^0.9253 , assuming τ _y =0, the constitutive equation is τ=2.4134D ^0.9745 , at this time the relative error (σ/%) is 9.01, The maximum relative error of the standard castor oil experiment is 10.6, so the converted equation τ=2.4134D ^1.00 , the fluid type is Newtonian fluid, and the correlation coefficient of the fitting equation R ² =0.9998;

The τ-D curves at different temperatures measured by the above method are shown in Figures 2, 3, 4, 5, and 6 respectively; it can be seen from the figures that: during the cooling process of the slag, when the temperature drops to the critical viscosity temperature, the slag The viscosity suddenly increases and solidifies rapidly, showing the characteristics of crystalline slag; with the increase of TiO ₂ content, the high-temperature viscosity of the slag shows a downward trend as a whole; The slag behaves as a Newtonian fluid; when the temperature is lower than the critical viscosity temperature, the slag appears shear thinning phenomenon, and the slag behaves as a non-Newtonian pseudoplastic fluid.

Example 2

The structure of the device for measuring the rheological properties of pyrometallurgical slag is the same as in Example 1;

Rheological property testing method is the same as embodiment 1;

The composition of the slag sample used is shown in Table 2;

Table 2 (wt%)

No. CaO SiO ₂ MgO Al ₂ O ₃ TiC TiO ₂ ∑ Alkalinity (CaO/SiO ₂ ) 1 30.73 27.94 8 14 2 17.33 100 1.10 2 31.08 28.25 8 14 4 14.67 100 1.10 3 31.43 28.57 8 14 6 12.00 100 1.10 4 31.78 28.89 8 14 8 9.33 100 1.10

Taking No.1 experiment as an example, the composition of the slag sample contains 30.73% by weight of CaO, 27.94% of SiO ₂ , 8% of MgO, 14% of Al ₂ O ₃ , 2% of TiC, and 17.33% of TiO ₂ ; , according to the constitutive equation, assuming τ _y ≠ 0, the constitutive equation is τ=-0.0727+1.5356D ^0.9929 , assuming τ _y =0, the constitutive equation is τ=1.5205D ^0.9953 , and the relative error (σ/%) is 1.73, less than the maximum relative error of the standard castor oil experiment 10.6, the converted equation τ=1.5205D ^1.00 , the fluid type is Newtonian fluid, and the correlation coefficient of the fitting equation R ² =0.9998;

The τ-D curves at different temperatures measured by the above method are shown in Figures 7, 8, 9, and 10 respectively; it can be seen from the figure that with the increase of TiC content in the slag, the overall viscosity of the slag increases; when TiC= 2% and the temperature is higher than the critical viscosity temperature of the slag, the slag behaves as a Newtonian fluid; when the temperature is lower than the critical viscosity temperature, the slag behaves as a non-Newtonian pseudoplastic fluid, and shear thinning occurs; when TiC≥4 %, yield stress is generated inside the slag, and the slag behaves as non-Newtonian Bingham fluid or plastic pseudoplastic fluid with temperature change; increasing the TiC content, the yield stress in the slag increases, and the shear thinning phenomenon is more significant .

Claims (9)

1. A device for measuring the rheological properties of pyrometallurgical slag is characterized in that it comprises an electric heating furnace, a crucible, a rheometer and a temperature control system; the electric heating furnace is fixed on the lifting device, and the crucible is fixed on the furnace of the electric heating furnace Inside the tube, the hook of the rheometer is connected to the rotor through the rotating rod, and the rotor is located inside the crucible; there is a gas channel at the bottom of the furnace tube, and the thermocouple in the furnace tube is assembled with the temperature control system. The temperature control system is assembled together, the rheometer is assembled with the computer, and the temperature control system is connected with the computer. 2. The device for measuring the rheological properties of pyrometallurgical slag according to claim 1 is characterized in that the furnace tube top of the electric heating furnace is provided with a rotating rod through hole, and there is a gap between the rotating rod through hole and the rotating rod. gap; the bottom of the furnace tube is provided with a crucible seat, the crucible is located on the crucible seat in the furnace tube, and the crucible is located in the cavity inside the heat preservation material. 3. The device for measuring the rheological properties of pyrometallurgical slag according to claim 1, characterized in that the lifting device is fixed on the support frame, the support frame is also provided with a fixed platform, and the rheometer is fixed on the fixed platform superior. 4. The device for measuring rheological properties of pyrometallurgical slag according to claim 1, characterized in that the material of the rotor is molybdenum; the material of the rotating rod is corundum. 5. The device for measuring rheological properties of pyrometallurgical slag according to claim 1, characterized in that the material of the crucible is graphite and the inner wall is provided with a lining, and the lining material is molybdenum. 6. A method for measuring the rheological properties of pyrometallurgical slag, characterized in that the device according to claim 1 is used to carry out in the following steps: (1) Crush the slag-like slag and place it in a crucible; (2) Introduce protective gas into the furnace tube and keep it in circulation; heat the slag sample to 1500±10°C through an electric heating furnace to form molten slag, and keep it warm for at least 1 hour; (3) Control the temperature in the furnace tube to cool down through the temperature control system. During the cooling process, test the rheological properties of the slag through a rheometer, and collect and analyze data through a computer until the data exceeds the range of the rheometer; (4) According to the corresponding shear stress at different shear rates measured by the rheometer, the rheological constitutive equation of the slag is established to determine the rheological characteristic parameters of the slag. 7. The method for measuring the rheological properties of pyrometallurgical slag according to claim 6, characterized in that in step (3), the temperature range of the rheometer test is 1350~1500°C, and it is carried out every 25±1°C Measurement. 8. The method for measuring the rheological properties of pyrometallurgical slag according to claim 6, characterized in that when the rheological properties of the slag sample are tested by a rheometer, the shear rate of the rotor is 2.5~43.4s ^-1 . 9. the method for measuring the rheological properties of pyrometallurgical slag according to claim 6, is characterized in that described constitutive equation adopts Herschel-Bulkley model: τ=τ _y +kD ⁿ ; Wherein, τ is shear stress , the unit is Pa; τ _y is the yield stress, the unit is Pa; k is the viscosity factor; D is the shear rate, the unit is s ^-1 ; n is the flow index.