CN106381395A - Method for recovering platinum group metal through car dead catalyst pyrogenic process - Google Patents

Abstract

The invention discloses a method for recovering platinum group metal through a car dead catalyst pyrogenic process. The method comprises the steps that 1, a dead catalyst is pretreated firstly to remove a metal shell and impurities on the surface of the dead catalyst, and then the pretreated catalyst is subjected to crushing and fine grinding; 2, iron powder, carbon powder and calcium oxide are mixed uniformly for standby application according to the mass ratio of (2-3):(1-3):(12-30); 3, the catalyst obtained after fine grinding and mixed flux are mixed, then added into a plasma electric-arc furnace to be heated, gradually heated up to 1773 K-2073 K, and fully stirred until complete melting is achieved; and 4, melt is gradually cooled to room temperature to obtain an iron alloy with the platinum group metal enriched and flux slag. According to the method, the extraction process is simple, the technological process is short, the influence on environment is small, and the recovery rate of the platinum group metal Pt reaches 99.99%.

Description

Method for recovery of platinum group metals by fire method of waste automobile catalyst

technical field

The invention relates to the technical field of recycling precious metals from automobile waste catalysts, and more specifically, to a method for recovering platinum group metals from automobile waste catalysts by fire method.

Background technique

Resource scarcity and environmental pollution are not only two major problems facing human development, but also major issues that need to be given priority in the implementation of sustainable development strategies in my country. As of the end of 2014, the number of automobiles in China reached 154 million, ranking second in the world. According to the prediction of the Ministry of Industry and Information Technology, the number of automobiles in my country will exceed 200 million by 2020. Automobile exhaust emissions make air pollution more and more serious, and automobile exhaust purification catalysts It is the key to solving the problem of automobile exhaust emissions. According to the current car ownership and growth rate in China, it is expected that my country will usher in the peak of car scrapping in the next few years, and the number of waste catalysts for scrapped cars will also increase significantly.

At present, the main goal of many countries for the treatment and disposal of waste vehicle exhaust catalysts is mostly to recover platinum group metals. The rough extraction process can be divided into two categories: pyrolysis and wet methods, which are the key to determining whether platinum group metals can be recovered efficiently. Wet recovery technology has the advantages of easy operation and low condition requirements. The recovery technology of automobile exhaust purification catalyst in my country is currently dominated by wet process. However, wet recovery process has a small processing capacity and has a great impact on the environment. With the increase in disposal demand, the country has higher and higher requirements for environmental protection, and the wet recovery process can no longer meet the needs of waste vehicle exhaust catalyst treatment and the purpose of environmental protection.

Contents of the invention

Aiming at the problems existing in the prior art, the object of the present invention is to provide a method for recovering platinum group metals by fire method of waste automobile catalysts. need.

The method for reclaiming platinum group metals by fire method of automobile waste catalyst of the present invention comprises the following steps:

Step (1): first pretreating the spent catalyst to remove the metal shell and easily separated impurities on the surface of the spent catalyst, and then crushing and finely grinding the pretreated catalyst;

Step (2): Prepare mixed flux: mix iron powder, carbon powder and calcium oxide in a mass ratio of 2 to 3:1 to 3:12 to 30 evenly for later use;

Step (3): After mixing the finely ground catalyst and mixed flux, add it to the plasma arc furnace for heating, gradually raise the temperature to 1773K ~ 2073K, fully stir until it is completely melted, and after high temperature slagging, the upper layer of the obtained melt is Slag layer, the lower layer is a liquid alloy layer containing platinum group metals;

Step (4): gradually lowering the temperature of the melt to room temperature to obtain a ferroalloy enriched in platinum group metals and flux slag.

Beneficial effects of the present invention: In the present invention, iron powder is used as a collector of platinum group metal elements, carbon powder is used as a reducing agent, calcium oxide is used as a flux, and high-temperature melting slagging is carried out by fire method, and platinum group metals are captured by iron to form platinum For palladium-rhodium-iron alloy, the slag with a lighter specific gravity will float above the heavier platinum-palladium-rhodium-iron alloy to separate the slag layer from the metal alloy and achieve the effect of enriching platinum group metals. Additives such as carbon powder and calcium oxide will be melted in the in the slag. In this method, the recovery rate of Pt in platinum group metals reaches 99.99%, the recovery rate of Pd reaches more than 99.22%, and the recovery rate of Rh reaches more than 90.12%, which is improved compared with the simple wet recovery rate, and the extraction process is simple and the process The process is short, the impact on the environment is small, and it has broad industrial application prospects.

detailed description

The present invention will be described in detail below in conjunction with specific embodiments. The description in this part is only exemplary and explanatory, and should not have any limiting effect on the protection scope of the present invention.

The method for reclaiming platinum group metals by fire method of automobile waste catalyst of the present invention comprises the following steps:

Step (1): first pretreating the spent catalyst to remove the metal shell and easily separated impurities on the surface of the spent catalyst, and then crushing and finely grinding the pretreated catalyst;

Step (2): Prepare mixed flux: mix iron powder, carbon powder and calcium oxide in a mass ratio of 2 to 3:1 to 3:12 to 30 evenly for later use;

Step (3): After mixing the finely ground catalyst and mixed flux, add it to the plasma arc furnace for heating, gradually raise the temperature to 1773K-2073K, stir fully until it is completely melted, and after high-temperature slagging, iron powder is used as platinum group metal Platinum-palladium-rhodium (Pt, Pd, Rh) collectors will capture platinum group metals to form platinum-palladium-rhodium liquid iron alloy, which has a relatively heavy specific gravity and will settle in the lower layer of the melt. Additives such as carbon powder and calcium oxide It will be melted in the slag, which has a light specific gravity and will float above the ferroalloy to form a slag layer;

Step (4): gradually lowering the temperature of the melt to room temperature to obtain a ferroalloy enriched in platinum group metals and flux slag. After the layered liquid iron alloy and solvent slag are cooled and solidified, they can be separated, and a small amount of magnetic materials in the solvent slag can be recovered by magnetic separation.

In the above technical scheme, in the step (1), the catalyst is crushed and finely ground to a particle size of less than or equal to 200 mesh, the finer the crushing, the more sufficient the iron captures the platinum group metals, and the shorter the melting time, it can save Slagging time.

In the above technical solution, in the step (3), the finely ground catalyst and the mixed solvent are added to the plasma arc furnace at a mass ratio of 5-15:1-3.

In the above technical solution, in the step (3), calcium oxide is continuously added during the stirring process until the slagging is completed, and the calcium oxide is used as a flux to reduce the viscosity of molten slag and improve the slagging efficiency.

Example 1

First cut and remove impurities such as the metal shell on the surface of the spent catalyst and easily separated expanded cotton, and then crush and finely grind the catalyst to 100 mesh; weigh 20g of iron powder, 10g of carbon powder, 120g of calcium oxide, and 2250g of catalyst and mix them evenly before adding plasma Heating in a body electric arc furnace, gradually raising the temperature to 1773K, fully stirring until it is completely melted, during the stirring process, calcium oxide can be continuously and slowly added until the slagging is completed, and the slagging time is 30 minutes. In the upper layer, the specific gravity of the liquid alloy containing platinum group metals is relatively heavy and sinks in the lower layer, so the upper layer of the obtained melt is a slag layer, and the lower layer is a liquid alloy layer containing platinum group metals; the melt is gradually cooled to room temperature, and the slag layer The heavy metals in the molten slag and the alloy layer will gradually solidify and separate, and finally obtain the iron alloy and flux slag enriched in platinum group metals. The contents of the platinum group metals platinum, palladium and rhodium in the iron alloy are detected respectively, and the recovery rate of platinum reaches 99.99%, the recovery rate of palladium reaches 99.22%, and the recovery rate of rhodium reaches 90.12%.

Example 2

First cut and remove impurities such as the metal shell on the surface of the spent catalyst and easily separated expanded cotton, and then crush and finely grind the catalyst to 100 mesh; weigh 30g of iron powder, 30g of carbon powder, 300g of calcium oxide, and 700g of catalyst and mix them evenly before adding plasma Heating in a body electric arc furnace, gradually raising the temperature to 2073K, fully stirring until it is completely melted, during the stirring process, calcium oxide can be continuously and slowly added until the slagging is completed, the slagging time is 20min, and the slag will automatically float after the high temperature slagging In the upper layer, the specific gravity of the liquid alloy containing platinum group metals is relatively heavy and sinks in the lower layer, so the upper layer of the obtained melt is a slag layer, and the lower layer is a liquid alloy layer containing platinum group metals; the melt is gradually cooled to room temperature, and the slag layer The heavy metals in the molten slag and the alloy layer will gradually solidify and separate, and finally obtain the iron alloy and flux slag enriched in platinum group metals. The contents of the platinum group metals platinum, palladium and rhodium in the iron alloy are detected respectively, and the recovery rate of platinum reaches 99.99%, the recovery rate of palladium reaches 99.42%, and the recovery rate of rhodium reaches 90.52%.

Example 3

First cut and remove impurities such as the metal shell on the surface of the spent catalyst and easily separated expanded cotton, and then crush and finely grind the catalyst to 200 mesh; weigh 20g of iron powder, 20g of carbon powder, 120g of calcium oxide, and 1200g of catalyst and mix them evenly before adding plasma Heating in a solid electric arc furnace, gradually raising the temperature to 1873K, fully stirring until completely melted, during the stirring process, calcium oxide can be continuously and slowly added until the slagging is completed, and the slagging time is 30 minutes. After slagging at high temperature, the slag will automatically float In the upper layer, the specific gravity of the liquid alloy containing platinum group metals is relatively heavy and sinks in the lower layer, so the upper layer of the obtained melt is a slag layer, and the lower layer is a liquid alloy layer containing platinum group metals; the melt is gradually cooled to room temperature, and the slag layer The heavy metals in the molten slag and the alloy layer will gradually solidify and separate, and finally obtain the iron alloy and flux slag enriched in platinum group metals. The contents of the platinum group metals platinum, palladium and rhodium in the iron alloy are detected respectively, and the recovery rate of platinum reaches 99.99%, the recovery rate of palladium reaches 99.62%, and the recovery rate of rhodium reaches 90.52%.

The above description is only a preferred embodiment of the present invention, and does not make any limitation to the technical scope of the present invention, so any minor modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention are still valid. It belongs to the scope of the technical solution of the present invention.

Claims (4)

1. A method for reclaiming platinum group metals by fire method of automobile waste catalyst, is characterized in that, comprises the following steps: Step (1): first pretreating the spent catalyst to remove the metal shell and easily separated impurities on the surface of the spent catalyst, and then crushing and finely grinding the pretreated catalyst; Step (2): Prepare mixed flux: mix iron powder, carbon powder and calcium oxide in a mass ratio of 2 to 3:1 to 3:12 to 30 evenly for later use; Step (3): After mixing the finely ground catalyst and mixed flux, add it to the plasma arc furnace for heating, gradually raise the temperature to 1773K ~ 2073K, fully stir until it is completely melted, and after high temperature slagging, the upper layer of the obtained melt is Slag layer, the lower layer is a liquid alloy layer containing platinum group metals; Step (4): gradually lowering the temperature of the melt to room temperature to obtain a ferroalloy enriched in platinum group metals and flux slag. 2. The method for recovering platinum group metals from waste automobile catalysts by fire method according to claim 1, characterized in that: in the step (1), the catalyst is crushed and finely ground until the particle size is less than or equal to 200 mesh. 3. The method for recovering platinum group metals by fire method of waste automobile catalyst as claimed in claim 1, characterized in that: in the step (3), the finely ground catalyst and the mixed solvent are in a mass ratio of 5 to 15:1 ~3 into the plasma arc furnace. 4. The method for recovering platinum group metals by fire from automobile waste catalysts as claimed in claim 1, characterized in that: in the step (3), calcium oxide is continuously added during the stirring process until the slagging is completed.