**4.3 Concentration reduced ore and model method**

The iron oxide groups showed that the limonite quality will enhance the quality of direct reduced iron ore quality as high iron grade. Further reductive roasting provides much higher metal conversion. The concentration model using Retort furnace and coal char was seen in **Figure 11**.

**Figure 12.** *TGA analyzes of the samples were carried out in Bubling bed in microwave radiated tube.*

#### **4.4 TGA analysis**

Analyzes were performed using approximately 300 g of limonite samples at a temperature range of 800–1000° C at a heating rate of 10° C / min. The temperature ranges and mass loss values obtained from the TG analysis are given in **Figure 12**. The limonite samples reduced 65% iron yield at 805°C, 899°C and 980°C, respectively. The limonite reduction was effective due to the core heat adsorbed on autonomous heating particle core by radiation.

In the TGA curves, the reduction rate values of the microwave activated limonite samples were determined to be lower than those of the native sample due to the increasing iron ore contents at 72–81%. The hematite, coal char shale and limonite samples revealed that the total mass losses at 1000°C were 31.9%, 47.75% and 38.15%, respectively.
