Hydrogen sulfide gas vacuum degassing tank

Abstract

To provide an evacuation tank having a structure capable of reducing a hole risk due to erosion generated in piping of a hydrogen sulfide gas flow.SOLUTION: There is provided a hydrogen sulfide gas evacuation tank that is installed in a sulfurization step in a hydrometallurgical smelting process for nickel oxide ore, the evacuation tank being an apparatus for performing gas-liquid separation of a sulfide slurry produced in the sulfurization step by a degassing treatment, obtaining gas-phase hydrogen sulfide gas and a slurry of solid-liquid components, and recovering the hydrogen sulfide gas, the hydrogen sulfide gas evacuation tank being characterized in that a conical baffle with an apex located at an upper portion and a doughnut-shaped baffle are located above a sulfide slurry inlet portion in the evacuation tank, and at least one combination of the conical baffle at an upper portion and at least one doughnut-shaped baffle at a lower portion is located.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a production apparatus in the field of wet smelting of nickel, and more particularly to the structure of a degassing tank for degassing dissolved hydrogen sulfide contained in a nickel sulfide slurry after a sulfidation reaction in a wet smelting process based on high-temperature and high-pressure sulfuric acid leaching for recovering nickel from nickel oxide ore.

Background Art

[0002] In the wet smelting of nickel oxide ore, a high-pressure acid leaching method, also referred to as the HPAL (High Pressure Acid Leaching) method, in which leaching treatment is performed with sulfuric acid under high-temperature and high-pressure conditions, is known. This high-pressure acid leaching method is an energy- and cost-efficient treatment method because it is wet-treated in almost all steps, unlike the dry smelting method in which the raw nickel oxide ore is subjected to reduction treatment or drying treatment. In addition, it also has the advantage that nickel and cobalt-containing mixed sulfides (also referred to as nickel-cobalt mixed sulfides) with a nickel grade increased to about 50 to 60% by mass can be produced from relatively low-grade nickel oxide ore raw materials.

[0003] The above high-pressure acid leaching method generally consists of a leaching step in which sulfuric acid is added to an ore slurry prepared by adding water to the raw nickel oxide ore and leaching treatment is performed under high-temperature and high-pressure conditions, a solid-liquid separation step in which leaching residues are separated and removed from the leaching slurry produced in the leaching step to obtain a leaching solution containing nickel and cobalt, a neutralization step in which a neutralizing agent is added to the leaching solution to separate and remove impurities contained in the leaching solution as neutralization precipitates to obtain a neutralization final solution, and a nickel recovery step in which a sulfiding agent is added to the neutralization final solution to recover nickel and cobalt as their mixed sulfides.

[0004] In the sulfidation step in the above nickel recovery step, hydrogen sulfide gas is blown in as a sulfiding agent to obtain nickel-cobalt mixed sulfides, and the slurry produced from the sulfidation step contains dissolved hydrogen sulfide gas that was not used in the reaction. Since hydrogen sulfide gas is generally a toxic substance, Patent Documents 1 and 2 describe equipment for degassing and recovering hydrogen sulfide contained in the slurry at the end of the sulfidation process to facilitate handling of the slurry. While gas-liquid separators like the one shown in Patent Document 3 are generally known for this purpose, the use of a cyclone allows for thorough separation of the gas, but the particles accelerated by the cyclone cause wear on the gas-liquid separator. Since the slurry produced from the sulfidation process contains a large amount of nickel-cobalt mixed sulfide as solid particles, it is particularly susceptible to wear, and it is reasonable to devise methods such as making maximum use of baffles without using a cyclone.

[0005] However, in a typical vacuum degassing tank (see Figure 1), the operating conditions are set to an environment below atmospheric pressure, which moves the hydrogen sulfide dissolved in the sulfide slurry to the gas phase and separates it from the gas. However, the degassed hydrogen sulfide gas may contain solid and liquid components of the sulfide slurry. This combination means that a small amount of sulfide slurry will enter the piping, which should only carry hydrogen sulfide gas, increasing the risk of erosion and hole formation in the piping due to the impact of slurry droplets. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-132945 [Patent Document 2] Japanese Patent Publication No. 2022-098258 [Patent Document 3] Japanese Patent Publication No. 2008-036503 [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention aims to provide a degassing tank having a structure that can reduce the risk of erosion-induced perforation in hydrogen sulfide gas flow piping. [Means for solving the problem]

[0008] Therefore, in order to solve the above problems, the inventors considered that by providing a cap-shaped baffle and a donut-shaped baffle above the slurry inlet to the degassing tank, the liquid and solid components accompanying the hydrogen sulfide gas degassed from the slurry could be trapped by these baffles, thereby preventing the liquid and solid components from flowing into the hydrogen sulfide gas flow. As a result of diligent research and development, they discovered a basic configuration of a reduced-pressure degassing tank consisting of a reduced-pressure degassing tank 100 and a vacuum pump (not shown) as shown in Figure 1.

[0009] In Figure 1, reference numeral 100 denotes a vacuum degassing tank which forms the basis of the present invention, reference numeral 100a denotes the tank body, reference numeral 101 denotes a sulfide slurry inlet insertion pipe, reference numeral 101a denotes a sulfide slurry inlet, and reference numeral 112 denotes a conical baffle (also called a cap-shaped baffle) with its apex positioned at the top. The sulfide slurry discharged from the slurry inlet 101a is received on the baffle surface, and gas-liquid separation is performed. The gaseous component, hydrogen sulfide gas, is removed to the outside from the gas outlet 114 at the top of the tank body 100a, while the liquid (slurry) component flows down the baffle surface and is removed to the outside from the slurry outlet 115 at the bottom of the tank body 100a.

[0010] Reference numeral 113 denotes a donut-shaped baffle, which is an inverted truncated cone-shaped baffle consisting only of sides with a vertically downward slope, and is placed on the inner surface of the tank body 100a. The liquid component separated by the upper cap-shaped baffle is received on the donut-shaped baffle surface, and gas-liquid separation is performed again. The hydrogen sulfide gas, from which the liquid component has been further removed, is removed to the outside from the outlet 114, and the remaining liquid component flows downward and is removed to the outside from the sulfide slurry outlet 115. As described above, the solid and liquid components are removed from the hydrogen sulfide gas that is released to the outside, making it possible to release hydrogen sulfide gas that contains as little solid and liquid components as possible. Furthermore, through research and development aimed at removing the solid-liquid components from the hydrogen sulfide gas, we have completed the present invention as shown in Figure 2.

[0011] A first aspect of the present invention is a vacuum degassing tank installed in the sulfidation step of a wet smelting process for nickel oxide ore, wherein the vacuum degassing tank is a device that separates the gas-liquid phase of the sulfide slurry generated in the sulfidation step by degassing treatment to obtain a gas-phase hydrogen sulfide gas and a slurry of solid-liquid components, and recovers the hydrogen sulfide gas, wherein the sulfide slurry inlet portion in the tank of the vacuum degassing tank Downward, A conical baffle with its apex positioned at the top. , and an inverted truncated cone-shaped baffle consisting only of sides with a vertical downward slope from the outer circumference to the inside, The conical baffle is located at the top, and at least one is located at the bottom. At least one set of inverted frustoconical baffles consisting only of the aforementioned sides is arranged, and above the sulfide slurry inlet in the tank of the reduced pressure degassing tank, a conical baffle with its apex positioned at the top, and an inverted frustoconical baffle consisting only of the aforementioned sides with a slope downward in a vertical line from the outer circumference to the inside is arranged, with the conical baffle at the top and at least one inverted frustoconical baffle consisting only of the aforementioned sides at the bottom This hydrogen sulfide gas vacuum degassing tank is characterized by having at least one set of baffle combinations arranged within it. [Effects of the Invention]

[0012] This invention reduces the risk of pipe perforation due to erosion occurring in the hydrogen sulfide gas piping recovered from the degassing tank, thereby enabling the extension of equipment maintenance periods and equipment lifespan, and resulting in significant industrial benefits in improving production efficiency. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram illustrating the basic vacuum degassing tank of the present invention. [Figure 2] This is a schematic diagram illustrating the vacuum degassing tank according to the present invention. [Modes for carrying out the invention]

[0014] The vacuum degassing tank according to the present invention is generally cylindrical in shape, and the sulfide slurry flows in from the side of the tank body. The slurry is discharged into the tank through the inlet via a slurry inlet insertion pipe. Therefore, the slurry flows from the center of the tank towards the bottom. The tank itself is depressurized from the top by a vacuum pump to a pressure below atmospheric pressure. As a result, when the sulfide slurry flows into the tank, the dissolved hydrogen sulfide in the slurry moves into the gas phase and is recovered as hydrogen sulfide gas from the top of the tank. The remaining sulfide slurry is recovered from the bottom of the tank.

[0015] The vacuum degassing tank according to the present invention is provided with at least one set of a combination of a conical baffle (also called a cap-shaped baffle) with its apex facing upwards above the slurry inlet to the degassing tank, and a donut-shaped baffle below it. This traps liquid and solid components accompanying the hydrogen sulfide gas degassed from the sulfide slurry on the baffle surface (in this case, the lower surface of the baffle), preventing the liquid and solid components from flowing into the hydrogen sulfide gas flow. This reduces the risk of erosion-induced perforation that occurred in the hydrogen sulfide gas flow piping.

[0016] The following will explain in detail using Figure 2. FIG. 2 is an explanatory view showing an embodiment of a vacuum degassing tank according to the present invention, where reference numeral 10 is the vacuum degassing tank according to the present invention, reference numeral 10a is the tank body, reference numeral 11 is a sulfide slurry inflow insertion pipe, reference numeral 11a is a sulfide slurry inlet, reference numeral 12 is a conical baffle (also referred to as a cap-shaped baffle) with its apex disposed at the upper part, which receives the sulfide slurry discharged from the inlet 11a on the baffle surface (in this case, the upper surface of the baffle), performs gas-liquid separation, removes the hydrogen sulfide gas as a gas component to the outside from the gas outlet 14 at the upper part of the tank body 10a, the liquid (slurry) component flows down along the baffle surface (upper surface), and is removed to the outside from the slurry outlet 15 at the bottom of the tank body 10a. Reference numeral 13 is a donut-shaped baffle, which is an inverted frustum-shaped baffle consisting only of the side surface with a slope provided vertically downward from the outer periphery to the inside, is disposed on the inner surface of the tank body 10a, receives the liquid component gas-liquid separated by the upper cap-shaped baffle 1 on its donut-shaped baffle surface (upper surface), performs gas-liquid separation again, removes the hydrogen sulfide gas from which the liquid component has been further removed to the outside from the outlet 14 at the top of the tank, and allows the remaining liquid component of the residue to flow downward and be removed to the outside from the sulfide slurry outlet 15 at the bottom of the tank.

[0017] Furthermore, in an embodiment of the present invention, above the inlet 11a, at least one set of a combination is provided, which includes a conical baffle (also referred to as a cap-shaped baffle) 1 with its apex at the upper part and a donut-shaped baffle 2 (an inverted frustum-shaped baffle consisting only of the side surface with a slope provided vertically downward from the outer periphery to the inside) below it. By doing so, the liquid and solid components entrained in the hydrogen sulfide gas degassed from the sulfide slurry are trapped on the baffle surface (in this case, the lower surface side of the baffle) of the cap-shaped baffle 1, and it is possible to prevent the liquid and solid from flowing into the hydrogen sulfide gas flow. Also, a similar treatment is performed on the baffle surface (lower surface of the baffle) of the donut-shaped baffle 2. The hydrogen sulfide gas removed to the outside as described above can be removed to the outside as hydrogen sulfide gas from which the solid-liquid components have been removed and which contains only a very small amount of solid-liquid components.

[0018] The "conical baffle (hat-shaped baffle) 1" and the "doughnut-shaped baffle (inverted truncated cone-shaped baffle with only the side surface) 2" located above the inlet 11a are preferably made of corrosion-resistant materials such as stainless steel, nickel, inconel, monel, hastelloy, etc. from the viewpoints of corrosion resistance and durability against hydrogen sulfide gas. Alternatively, the member having the surface for gas-liquid separation may be coated with a material having corrosion resistance against sulfides and hydrogen sulfide gas.

Example

[0019] When the degassing tank according to the present invention as described above was used in the sulfidation step in a wet smelting process based on high-temperature pressurized sulfuric acid leaching for recovering nickel from nickel oxide ore, and the operation was carried out, a hat-shaped baffle 1 was provided above the sulfide slurry inlet 11a into the tank body, and a doughnut-shaped baffle 2 was provided below it. As a result, it was confirmed that the liquid and solid components accompanying the hydrogen sulfide gas recovered from the degassing tank were reduced, and clogging of the piping holes in the recovered hydrogen sulfide gas piping did not occur.

Explanation of Reference Numerals

[0020] 1 Conical baffle / hat-shaped baffle (baffle arranged above the inlet 11a) 2 Doughnut-shaped baffle / inverted truncated cone-shaped baffle 10 Vacuum degassing tank according to the present invention 10a, 100a Tank body 11, 101 Sulfide slurry inlet insertion pipe 11a, 101a Sulfide slurry inlet 12, 112 Conical baffle / hat-shaped baffle (baffle having a vertex at the top) 13, 113 Doughnut-shaped baffle / inverted truncated cone-shaped baffle (baffle consisting only of the side surface with a slope downward along the vertical line) 14, 114 Gas outlet 15, 115 Slurry outlet 100 Conventional vacuum degassing tank

Claims

[Claim 1] A vacuum degassing tank installed in the sulfidation step of a wet smelting process for nickel oxide ore, The aforementioned vacuum degassing tank is a device that separates the gas-liquid phase from the sulfide slurry generated in the sulfidation process by degassing, obtaining a gas-phase hydrogen sulfide gas and a solid-liquid slurry, and recovers the hydrogen sulfide gas. Below the sulfide slurry inlet in the vacuum degassing tank, at least one set of a combination is arranged, consisting of a conical baffle with its apex positioned at the top and an inverted frustoconical baffle consisting only of sides with a vertical downward slope from the outer circumference inward, with the conical baffle at the top and at least one inverted frustoconical baffle consisting only of sides at the bottom. A hydrogen sulfide gas vacuum degassing tank is characterized in that, above the sulfide slurry inlet in the vacuum degassing tank, at least one set of a conical baffle with its apex positioned at the top and an inverted frustoconical baffle consisting only of sides with a vertical downward slope from the outer circumference to the inside is arranged, with the conical baffle at the top and at least one inverted frustoconical baffle consisting only of sides at the bottom.

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