JPH0142883B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to titanium carbide powder or titanium carbide graphite made from TiO ₂ in the leaching residue discharged from the apple grading leaching process of ilmenite with hydrochloric acid or sulfuric acid and various carbon materials. The present invention relates to a method for producing Aite mixed powder particles.

The main purpose of the present invention is to recover Ti compounds mainly consisting of fine rutile-type TiO ₂ in the leaching residue discharged from the hydrochloric acid or sulfuric acid leaching process of Illunite, which has conventionally been discarded without being particularly utilized as leaching residue. As one of the new effective utilization methods, SiO ₂ and Cr ₂ O ₃ contained in the residue, especially in the pretreatment process, are
Fine titanium carbide powder is produced through carbonization and deoxidation reactions at high temperatures and high vacuum without removing impurities such as, and exhibits excellent properties as an abrasive or wear-resistant material, or carbonized as a product with added lubricity. The objective is to develop a method for producing mixed powder of titanium and graphite.

The ilmenite leaching residue contains Ti compounds mainly composed of rutile-type TiO ₂ as well as Fe ₂ O ₃ , SiO ₂ , Al ₂ O ₃ ,
It contains unreacted components such as Cr ₂ O ₃ and is generally extremely fine.

At present, the leaching residue is neutralized, washed with water after adding an appropriate supernatant, and then disposed of. Its composition varies over a wide range depending on the origin of the raw ilmenite, leaching conditions, etc. As an example, show the composition of the sulfuric acid leaching residue of a 7:4 mixture of Malayan ilmenite and Australian ilmenite. The example is as follows.

Example of composition of sulfuric acid leaching residue (wt%) TiO ₂ : 43.14%, Fe ₂ O ₃ : 16.36%, SiO ₂ : 7.62
%Al ₂ O ₃ : 0.72%, Cr ₂ O ₃ : 0.06% As shown above, the TiO ₂ grade is high and its effective utilization is desired, but all of the compositional components in the leaching residue are metal oxidizing components and are extremely Since the particles are fine, it is extremely difficult to recover TiO ₂ in a sufficiently high grade in the flotation concentrate or tailings even if a method known as a separation method for fine particles such as flotation is applied. However, now that we are on the path to lower quality as resources are depleted, it is not appropriate to dispose of this leached residue from the standpoint of effective resource utilization.

On the other hand, currently, titanium carbide is produced by reducing and carbonizing high-purity TiO ₂ minerals, such as rutile or anatase, as a raw material mineral.

Generally, the carbonization reaction of TiO ₂ is expressed as TiO _{2 (s)} + 3C _(s) = TiC _(s) + 2CO _(g) (1). From an equilibrium standpoint, this reaction is thought to proceed at a fairly low temperature, but for industrial production purposes, it is necessary to use a high temperature of, for example, several hundred degrees, from a kinetic standpoint. . If it is possible to remove other oxides such as SiO ₂ or Cr ₂ O ₃ from the system in such a high temperature range, high purity titanium carbide can be produced using the ilmenite leaching residue as a starting material. becomes possible.

If titanium carbide is produced by the reaction of formula (1), the C/O ratio required for the reaction should be 1.5 in terms of molar ratio, but if TiO ₂ is carbonized under these conditions, Carbon inevitably remains in the product. The carbon material added to this reaction may be amorphous carbon with strong reaction activity or graphite, but since the reaction is a high temperature reaction, the excess carbon that does not directly participate in the reaction will be In objects, it takes the form of graphite.

The reasons why the chemical quantitative mixing of formula (1) is not required in the actual reaction are as follows: (1) When TiO ₂ , which has a high oxygen potential, reacts with carbon at a low temperature in the initial stage of reduction, the reaction product is As shown in equation (1), it is degassed not as CO but rather as CO ₂ .

(2) Possible reasons include that TiO produced during the reduction process is volatile, so excess oxygen is removed. The volatility of lower oxides is also the same for other Si and Cr oxides, and because the lower oxidation of these impurities occurs at lower temperatures than TiO, these elements are less volatile. Removal becomes possible.

Experimental results supporting these inferences include adding high-purity graphite powder for electrodes to the sulfuric acid leaching residue of ilmenite so that the molar ratio of C/O to TiO ₂ in the residue is 1.45. When molded under a pressure of cm ² and reacted for 1 hour at 1900° C. and 10 ⁻⁴ Torr, a mixed product of titanium carbide and graphite containing 28.32 wt% carbon and 390 ppm residual oxygen is obtained. The X-ray diffraction image of this product is shown in FIG.

As is clear from this figure, no X-ray diffraction peaks other than titanium carbide and graphite phases are observed. In fact, the results of emission spectroscopic analysis of this product are as follows.
The presence of very small amounts of Si, Cr, V, Zr, B, Fe, Al, and Zn indicates that the impurities present in the residue were almost completely removed from the system. There is.

Theoretically, a mixed phase of titanium carbide and graphite is formed at an atomic weight ratio of C/Ti>0.95, and C/Ti
Ti: It is known that a single phase of titanium carbide occurs in the range of 0.53 to 0.95.

When the same residue is pressure-molded to a C/O molar ratio of 1.35 and subjected to reductive carbonization at a temperature of 1600° C. and 10 ⁻⁴ Torr for 2 hours, a single phase of titanium carbide is produced as shown in FIG. 2. In this case, for example, no X-ray diffraction peaks of carbides and oxides of SiC or other impurities are observed.

The present invention will be explained below with reference to Examples.

Example 1 As starting materials, a product obtained by washing, filtering, and drying the sulfuric acid leaching residue of ilmenite and a commercially available graphite powder for electrodes (99.99%, 200mesh) were used.The former contained _TiO2 : 43.14%, Fe: 11.44%,
It contains Al ₂ O ₃ : 0.72% and Cr ₂ O ₃ : 0.06%. Graphite is mixed at a molar ratio of C/O=1.48 based on O in TiO ₂ contained in the leaching residue, and formed into a columnar shape under a pressure of 300 Kg/cm ² . The amount of dried residue used at this time was 92.59 g, and the amount of graphite used was 17.76 g. This temperature is 1900
C. and a final vacuum of 10.sup. ^-4 Torr for 1 hour, a silver-black product with a carbon content of 62.42 at% and residual oxygen of 360 ppm was obtained. Phase identification of this product by X-ray diffraction revealed that it was a mixture of TiC and graphite, and the lattice constant of TiC was 4.3308 Å.

Example 2 Using the same starting materials as Example 1 and C/O molar ratio
Graphite was added to give a particle diameter of 1.42, followed by mixing and molding, followed by reduction carbonization at 1900°C and 10 ^-4 Torr for 1 hour. The resulting product is a silver-black powder containing 61.77 at% carbon and 250 ppm residual oxygen.
X-ray phase identification results show that the product is a mixture of TiC and graphite. The lattice constant of the obtained TiC was 4.3305 Å.

Example 3 Using the same starting materials as Example 1 and C/O molar ratio
After adding graphite to a concentration of 1.35, it was mixed and molded, and subjected to reduction carbonization for 2 hours at 1600℃ and 10 ^-4 Torr.
A silver-black particle product was obtained. The results of X-ray phase identification indicate the formation of a TiC single phase with a lattice constant of 4.3303 Å. The carbon content of the product was 46.06 at% and the residual oxygen was 374 ppm.

[Brief explanation of drawings]

FIG. 1 is an X-ray diffraction diagram of a mixed powder of titanium carbide and graphite obtained according to the present invention. FIG. 2 is an X-ray diffraction diagram of titanium carbide powder obtained according to the present invention.

Claims (1)

[Claims] 1 After drying the sulfuric acid or hydrochloric acid leaching residue of ilmenite, add amorphous carbon or graphite in an amount such that the C/O molar ratio is 1.0 to 2.0 with respect to 0 of TiO ₂ contained in the above residue. To obtain powder particles of titanium carbide or a mixture of titanium carbide and graphite with a low level of impurity content by compression molding and carbonization under high vacuum at temperatures ranging from 1400 °C to 2700 °C in a vacuum furnace. Characteristic manufacturing method of titanium carbide.