64:1 If something is forbidden to be eaten by the Torah, even if it is permitted to benefit from that thing, one may not do business with it or use it as collateral for a loan. One may not even buy it in order to feed his non-Jewish workmen. One may, however, engage in business using something that is not intended for food, such as horses and donkeys. One is permitted to do business using non-kosher fat since the Torah tells us that, aside from eating, "It may be used for any purpose" (Leviticus 7:24).
64:2 If a person happened to acquire a forbidden item - for example, if a non-kosher fish was caught in his net or a mortally-wounded animal wandered onto his property - one may sell it because it was not his intention to pursue business in this way. He must, however, sell it immediately and not delay in order to fatten it up. He may sell the item using an agent, even if the agent also profits from his involvement in the transaction. The agent may not purchase the thing for himself because that would constitute the agent intentionally trading with forbidden items.