Method for utilizing sulfur-containing refining waste residue for refining slag

Abstract

The invention relates to a method for recycling sulfur-containing refining waste residue generated in the process of liquid steel refining for refining slag, which is characterized by taking cooling pulverization pretreatment fine powders, roasting the sieving fine powders in the weak oxidizing atmosphere that an oxygen partial pressure is between 0.08 and 0.15atm at a temperature of more than or equal to 1100 DEG C to convert a harmful component CaS to an effective component CaO so as to remove sulfur impurities, and decomposing calcium hydroxide. In the method, the recycling of the sulfur-containing refining waste residue is directly used for reusing the refining slag with high utilization value, and the maximum utility value of the abandoned sulfur-containing refining slag is fully exerted. Compared with the conventional technology application, the invention can increase the value added for each ton of the abandoned sulfur-containing refining slag by more than 800 RMB. Moreover, the sulfur in the sulfur-containing refining waste residue is removed by a simple oxidizing and roasting process to guarantee the cleanliness of the recyling product, the liquid steel resulfurization can not be caused in the recycling process of carrying out the liquid steel desulfuration, the cumulative effect of the sulfur can not be generated in the metallurgy process, and a novel way of recycling the sulfur-containing refining slag is developed.

Description

technical field The present invention relates to a recycling method of iron and steel metallurgical waste slag, especially about the sulfur-containing refining slag produced by molten steel refining, which is desulfurized by oxidation and roasting, and CaS is transformed into CaO with desulfurization effect, which is directly used as recycling of refining slag method. Background technique For every ton of steel refined, about 10-20 kg of sulfur-containing refining waste is produced. In 2008, my country's steel output exceeded 500 million tons, and the annual output of sulfur-containing refining waste will reach 5-10 million tons. Compared with the original refining slag or premelted slag, the reducing slag has the following advantages: (1) Higher alkalinity, rich in CaO and Al necessary for molten steel refining 2 o 3 Composition; (2) The oxidizing property of the slag is very low, (FeO+MnO)=0.5~3.0%, which is equivalent to the content of the original refining slag; (3) Th...

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Problems solved by technology

However, the sulfur content in this sulfur-containing refining waste residue is relatively high, reaching 0.8-2.0wt%. Direct recycling will lead to problems such as sulfur enrichment and secondary pollution of molten steel. Thermodynamic calculations show that the sulfur in the sulfur-containing refining waste When 0.8wt% is reduced to 0.05wt%, under the same conditions, the "sulfur capacity" value of the slag can be increased by about 20 times. When the content is less than 0.1wt%, the recycling of sulfur-containing refining waste residue will have extremely high social and economic value

Such a huge amount of newly added reducing slag plus the accumulation year by year has caused great pressure on the environment and is also a waste of useful resources

At present, the treatment methods of metallurgical sulfur-containing refining waste slag are different among steel mills: for example, they are mixed with ordinary converter slag and piled up in the slag yard for treatment. They are mainly used for road construction or cement production. These utilization methods are not only environmentally The pollution is serious, and the utilization value is extremely low, wasting a lot of useful resources in vain

There is also technology to transform sulfur-containing refining waste slag for other purposes in steelmaking to increase the utilization value of refining waste slag. For example, Chinese patent CN101433950A uses recycled refining slag to prepare continuous casting mold slag, but because the recovered refining slag contains sulfur and the sulfur content fluctuates relatively Large, the use of mold slag products may lead to sulfur increase in molten steel

Chinese patent CN1865458 discloses the use of LF furnace refining waste slag to make pellets and return it as a slagging agent for steelmaking, but the amount of use is relatively limited. The molten steel in the converter smelting process has a tendency of "returning sulfur", and the added value of the product is not high.

Chinese patent CN1597997 discloses a cascade utilization method of steelmaking slag, which fine-tunes the composition of the slag produced in the later process and returns it to the previous process step by step, but this method will lead to the enrichment and accumulation of impurity elements such as P and S in the process, resulting in unnecessary Increased energy consumption increases the possibility of secondary pollution of molten steel

Chinese patent CN1804047 discloses a recycling method for the remaining hot steel slag in steelmaking. Like Chinese patents CN1597997 and CN1865458, there is a phenomenon of cyclic enrichment of impurity elements, which is very unfavorable for smelting high-quality clean steel.

It can be regarded as one of the better ways to recycle refining waste slag, but because the sulfur in the raw materials cannot be removed, the molten steel will be polluted during recycling, and the scope of its recycling is also very narrow.

As mentioned above, although people have confirmed that the sulfur-containing refining waste residue has high utilization value, they have also tried to carry out various recycling treatments on this kind of waste residue, but they all have the same problem. Since the sulfur cannot be effectively removed, if recycled for value Refining slag with high consumption and high consumption will make the sulfur in the sulfur-containing refining waste slag gradually enriched in the recycling process and lose the desulfurization effect, increase energy consumption and pollute molten steel, thus limiting the scope of recycling of sulfur-containing refining waste slag and effect, which reduces the value of recycling, and can only be used for relatively low-value applications such as sinter as a flux, slagging agent, converter slagging agent, and covering agent.

For a long time, those skilled in the art have tried to remove the sulfur impurities in the sulfur-containing refining waste slag so that it can be reused as a high-value refining slag, but no effective method has been found, so the maximum utility and value utilization of the reducing slag has not been achieved.

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