75090
William Bleloch ( 9 February 1906 Johannesburg - 20 June 1991 ) was a South African metallurgist noted for developing smelting techniques for the processing of chrome ores .
 Johannesburg
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Johannesburg