The so-called Stelco-Lurgi/Republic Steel-National Lead (SL/RN) process is a widely used coal-based DRI-making process which uses a rotary kiln. The process uses lump ore, pellets, beach sand or ilmenite ore and solid carbon to produce hot or cold DRI. The process operates at high temperature and atmospheric pressure.

The advantage of this technology is its robustness and the potential to use low-quality coal, which makes it well suited for developing countries such as India and South Africa. This process generates significant amounts of residual gas, which is used for power generation. However, coal consumption is considerably higher than for a blast furnace and the energy efficiency of individual plants depends on the efficient use of the large amounts of residual gas isSL/RN process is a kiln based process that uses . This is the most widely used coal based direct reduction process.  The final metallization is about 93% and carbon content about 0.1 to 0.2%.