and fortunately i found it, and right now i want to share it with you guys.
- Place the ore in the smelter, and then place the coals. ( Thanks to Borka. )
-Leave that stuff for 16 minutes and 39 seconds without clicking anything.( Thanks to Borka Again. )
- When the time passed, go and click " Light " button, and leave the ores to get smelted.
- After the required time passed, your ores are all smelted.
Congratulations

* I wanted to mention that;
- The character who mined the ores will affect how many bars you can get from the ores, not the character who smelts it.
So, mine with a character which have full industry belief, with doing that you will get more bars when compared to any character who doesn't have full industry belief.
- And i suggest you all to use the charcoal with the possible greatest quality, you'll feel the difference when you use high quality equipment.
Good Luck...