Beef and Black Bean Soup

1 lb. ground beef, browned
4 c. chicken stock
1 can diced tomatoes
1/2 c. onion, diced
3 med. carrots, diced
2 celery ribs, thinly sliced
2 garlic cloves, minced
1 1/2 tsp. dried basil
1 tsp. salt
1/2 tsp. dried oregano
1 tsp. cumin
1/2 tsp. chili powder
2 cans (15 oz.) black beans, rinsed and drained
1 1/2 c. rice

Place beef in slow cooker. Add remaining ingredients except beans and rice. Cover and cook on high 1 hour. Reduce to low and cook 4-5 hours or until vegetables are tender. Add beans and rice. Cook 1 hour longer on low or until heated through.