Plastic bottle caps should now be left ON empty bottles for recycling. New processing technology allows caps to be collected and recycled while attached to a bottle. Plastic bottles with caps are sorted at the materials recovery facility, perforated, and baled. The baled bottles and caps are purchased as a raw material by a manufacturer or processor. The manufacturer or processor shreds the bottles and caps into flakes which are put through a float tank to separate the different plastic types for end use.
A bottle cap which is separate from a bottle is too small to be sorted in a materials recovery facility and will probably end up as trash for landfill or incineration. Please empty your bottles, replace the caps, and deposit them in a recycling bin.