Company “Nornickel”, Polar Division, Norilsk, Russia:

R. A. Marchuk, Chief Specialist Laboratory of Engineering Support of Production at Nadezhdinsky Metallurgical Plant named after B. I. Kolesnikov, Center for Engineering Support of Production, e-mail: marchuk.nor@rambler.ru
L. V. Krupnov, Deputy Head of the Scientific and Engineering Administration — Chief Metallurgist, e-mail: Krupnovlv@nornik.ru
V. I. Morgoslep, Melting Shop Superintendent, Nadezhdinsky Metallurgical Plant named after B. I. Kolesnikov, e-mail: morgoslepvi@nornik.ru

Gipronickel Institute, Saint Petersburg, Russia:
D. V. Rumyantsev, Chief Specialist, e-mail: RumyantsevDV@nornik.ru

The issues of skull formation in flash smelting furnaces (FSF) in the Company “Nornickel” and ways to solve them are considered. The problem of formation of refractory skulls in the FSF of Nadezhdinsky Metallurgical Plant (NMP) has arose quite a long time ago. Initially, the main cause for the skull formation was the need to process the products that are not typical for smelting in the FSF, such as nickel slag from the Copper plant, stale pyrrhotite concentrate, and concentrates from holding ponds, since they contain rather large quantity of refractory compounds, such as nickel ferrite, magnetite, and nickel oxide. Moreover, the concentrates coming to be smelted in the FSF began to contain the increased non-metallic fraction, comprising refractory peridots, pyroxenes and plagioclases. Because of a closure of the Nickel plant, the volume of the indicated products has increased, which led to a decrease of the sulfur content in the mixture of concentrates up to 26% on average. It should be noted that before the Nickel plant closure (in 2015), the sulfur content in a condensed nickel-sulfide concentrate has averaged at least 30%. In connection with the conversion of Talnakh Concentrator to a new oredressing technology in 2016, granulometric composition of the nickel-pyrrhotite concentrate being sent to NMP has also changed significantly, and the content of a slime fraction –0.011 mm has increased. Recently, there has been noted that the flue gas path in the FSF, the uptake contiguity to the waste heat boiler as well as the discharge part of the waste heat boiler have been overgrown with skull and dust sediments. This reduces the output of the furnaces and requires their periodic unplanned stops. In the context of the work, an analysis of the skull formation in the furnaces was carried out, as well as a search for technological solutions of both combating already formed skulls, and preventing their subsequent occurrence. At present, some of the measures intended to combating skulls have been successfully implemented, while the work in other areas continues.

1. Krupnov L. V. Mechanism of formation of refractory skull in flash smelting furnaces and ways of its removal: Dissertation … of Candidate of Engineering Sciences. Saint Petersburg : Mining University, 2015. 234 p.
2. Midyukov D. O., Umysheva A. A., Chikildin D. E., Smirnov Yu. A. Ore preparation at Talnakh Concentrator with the semi-autogeneous grinding introduction. Tsvetnye Metally. 2018. No. 6. pp. 27–31. DOI 10.17580/tsm.2018.06.03.
3. Selivanov E. N., Gulyaeva R. I. Toloknov D. A. Magnetite precipitation on melting of copper-zinc concentrates in Vanyukov furnace. Tsvetnaya Metallurgiya. 2010. No. 7. pp. 3–9.
4. Vieira L., Marques M., Leite F. Flash furnace thermal control at Paranapanema. Proceedings of the XV International Flash Smelting Congress. Helsinki, 2017.
5. Jian-Ping H., Zheng-Bin W., Jin-Jun F. The overview of progress at Jinlong smelter in recent years. Proceedings of the XV International Flash Smelting Congress. Helsinki, 2017.
6. Anapolskaya S. G., Marchuk R. A., Petrov A. F., Yuriev A. I. Operation of flash smelting furnaces in the Polar Division of PJSC “MMC” Norilsk Nickel” on processing of the low-energy raw material. Tsvetnye Metally and Minerals 2017 : collection of reports of the Ninth international congress. Krasnoyarsk : Nauchno-innovatsionnyi centr, 2017. pp. 1150–1155.
7. Marchuk R. A., Krupnov L. V., Velichko V. V. The processing peculiarities of the finely dispersed raw material with reduced energy potential in an autogenous melting unit. Tsvetnye Metally and Minerals 2017 : collection of reports of the Eleventh international congress. Krasnoyarsk : Nauchnoinnovatsionnyi centr, 2019. pp. 855–861.
8. Anapolskaya S. G., Petrov A. F., Fomichev V. B., Krupnov L. V., Tyuleneva D. I. Processing of sulfide ore raw material during flash smelting under the lowering conditions of its heating value. Tsvetnye Metally and Minerals 2014 : collection of reports of the Sixth international congress. Krasnoyarsk : Sibirskyi federalnyi univeristet, 2014. pp. 578–584.
9. Danilov M. P., Shapovalov V. A., Tsybizov V. D., Anapolskaya S. G., Severilov A. V. Industrial testing for working through the operating modes of a new charge sprayer. Tsvetnye Metally. 2004. No. 11. pp. 28–30.
10. Drorbaugh D., Loveless M., Ochoa K., Walton R., Wilde R. Recent improvements at the Kennecott copper smelter. Proceedings of the XV International Flash Smelting Congress. Helsinki, 2017.
11. Sanchez A., Ramos M., Garcia J. Improvements carried out in the FSF up-take shaft and waste-heat boiler – a review over Atlantic Copper’s history. Proceedings of the XV International Flash Smelting Congress. Helsinki, 2017.
12. Sinev L. A., Borbat F. V., Kozyura A. I. Flash smelting of sulfide concentrates. Moscow : Metallurgiya, 1979. 150 p.