Cobalt is a vital metal in the modern society because of its applications in lithium-ion batteries, super alloys, hard metals, and catalysts. Further, cobalt is a representative rare metal and is the 30th most abundant element in the Earth’s crust. This study reviews the current status of cobalt extraction and recycling processes, along with the trends in its production amount and use. Although cobalt occurs in a wide range of minerals, such as oxides and sulfides of copper and nickel ores, the amounts of cobalt in the minerals are too low to be extracted economically. The Democratic Republic of Congo (DRC) leads cobalt mining, and accounts for 68.9 % of the global cobalt reserves (142,000 tons in 2020). Cobalt is mainly extracted from copper–cobalt and nickel–cobalt concentrates and is occasionally extracted directly from the ore itself by hydro-, pyro-, and electro-metallurgical processes. These smelting methods are essential for developing new recycling processes to extract cobalt from secondary resources. Cobalt is mainly recycled from lithium-ion batteries, spent catalysts, and cobalt alloys. The recycling methods for cobalt also depend on the type of secondary cobalt resource. Major recycling methods from secondary resources are applied in pyro- and hydrometallurgical processes.

Because of its unique properties, tungsten is a strategic and rare metal used in various industrial applications. However, the world's annual production of tungsten is only 84000 t. Ammonium paratungstate (APT), which is used as the main intermediate in industrial tungsten production, is usually obtained from tungsten concentrates of wolframite and scheelite by hydrometallurgical treatment. Intermediates such as tungsten trioxide, tungsten blue oxide, tungstic acid, and ammonium metatungstate can be derived from APT by thermal decomposition or chemical attack. Tungsten metal powder is produced through the hydrogen reduction of high-purity tungsten oxides, and tungsten carbide powder is produced by the reaction of tungsten powder and carbon black powder at 1300–1700oC in a hydrogen atmosphere. Tungsten scrap can be divided into hard and soft scrap based on shape (bulk or powder). It can also be divided into new scrap generated during the production of tungsten-bearing goods and old scrap collected at the end of life. Recycling technologies for tungsten can be divided into four main groups: direct, chemical, and semi-direct recycling, and melting metallurgy. In this review, the current status of tungsten smelting and recycling technologies is discussed.

The present study is the development of recyclable micro pale expansion drilling bit. The domestic market will gradually be suppressed by the new developed ring one in the use of ring bit(non-recyclable) in this business. Existing casing drilling and insertion method is applied by order of the casing inserted after drilling, which has the disadvantage that a long construction time, device costs and labor consuming. When the steel pipe multi-bit-only expansion drilling is developed, enterprise sales and employment effects can occur. If the performance of the developed products through the product equal to or superior to the domestic component parts are developed proprietary technology acquisition and cost savings, as well as the construction period of about 30%, and the expected reduction of 70% in material costs are expected.

Ceramic welding backing material is a mullite-cordierite composite that is currently being used for welding processes in plant and shipbuilding. It is the optimal material for welding processes thanks to its extremely low thermal expansion coefficient and strong resilience against high temperature. However, due to the pollutants from welding such as iron and carbon, the entire amount of ceramic welding backing material is being land-filled after a single-time use. In this study, ceramic welding backing material was mixed with clay and kaolin to be used as a new ceramic body. A composition with 20 ~ 50% of ceramic welding backing material showed sufficient plasticity, and when fired at 1,250oC, it was deemed available for ceramic block and others with the porosity of 2.27 ~ 5.94%, water absorption ratio of 0.99 ~ 3.96% and bending strength of 720 ~ 810 kgf/cm2. In addition, color ceramic body, which was made from a waste welding backing material, of which iron was partially removed, added with 3wt% of high temperature pigment and fired at 1,250oC, displayed the unique color of the pigment, meaning that waste welding backing material could be used for ceramic bodies of a variety of colors.