Scrap metal dealers take a wide variety of metals including types that can and cannot be thrown into the recycling bin. Karung Guni will usually act as middlemen so most thing you would sell to a scrap dealer will also likely be bought by a karung guni but at a much lower price.
Scrap dealers will not deal in very small volumes so be sure you have at least a kilogram of material to sell.
These businesses are typically found in industrial areas. Many also advertise their businesses on Carousell.