The demand for zinc increased in World War II because the United States needed soft lead for small arms ammunition production. Before the war, much zinc was discarded because it was not easy to.
The U.S. government selected the International Smelting & Refining Co to build a plant in Tooele to process zinc in 1940. They chose this area because of the large concentration of lead smelters and slag dumps in the area.
Molten slag containing lead and zinc is tapped from the blast furnace in its molten state, and then dumped in the new zinc furnace cooled by a water jacket. Cold slag from the slag dump was also added to the molten slag in the furnace. This became the source material to extract zinc and lead.
They added pulverized coal to the bottom of the zinc furnace with highly pressured air and created a very hot fire. This caused the lead and zinc to boil out of molten slag. The combination zinc and lead fumes over the molten slag was removed by powerful suction and cooled through a serious of tubes. Then, it was collected into thousands of vertical bags 36 inches in diameter and 40 feet high. The bags were made of unscoured wool, and later fiber glass, and finally orlan and nylon. 
 Next, fans blew the content of bags into an 80 foot long, 8 foot diameter brick-lined kiln to be dried out. The kiln was heated to 3,000 degrees and caused the lead to dry a fine dust which was pure lead oxide. The lead oxide was used for bullets during the war. Later, the lead oxide was sold to Sherwin Williams for lead paint, and the plant could change the color from pure white to light yellow by altering the temperature. The in the kiln fuse into various sized pellets as high-grade zinc oxide. After collection, it was shipped to refineries in the East. 
 Without adding the zinc plant to the smelter complex, the smelter may have been shutdown in the 1940s.

Taken from Claude Atkin’s Notes from September 1983)

A Story about the Aerial Tramway over the ridge of the Oquirrh Mountains by Frank Dunlavy

“An aerial tramway was also constructed totransport the ores from the mines of hte Utah Delaware Minng Company, and other mines, in the Bingham District, The tramway was 20,000 feet long and was build by the Trenton Iron Works. The loading station was located at the Highland Boy mine and the ore was delivered in buckets of 1200 pounds capacity, spaced 200 feet apart and traveled at a rate of 600 feet per minute. The ore was dumped into the smelter terminal bins. Later, after the concentrators were built, special termain bins were built for this department just short of the main terminal building. From the main terminal bins the ore was drawn into special 50-ton motor dump cars, weighed, and delivered to the smelter receiving bins.

Perhaps the reader will not object if the write recounts a personal experience associated with this aerial tramway. I worked for International for forty-three years, mostly in the lab, but also all over the plant when things were slow. I rode on this aerial tram several times. It was my first ride that I would like to tell you about. This ride occured in about 1929 or 1930.

I can, over fifty years later, still vividly recall this frightening experience. First, I had to climb the narrow iron stairway of the five-story Tooele-side terminal andlook down some 75 feet through the wide opening or window where both the incoming and outgoing buckets were moving. I noticed that the four- inch steel cable to which the ore buckets were affixed seemed to be alive as it vibrated up and down and side to side. I puased for a moment to watch as the buckets coming in were switched one by one onto a circular siding and, still moving, were guided by a workman, then braked over one of the large (2,000 ton capacity) recieving bins. The main cable continued to the endo fhte building, then curved around so that it was now travelling in the opposite direction. After the ore was dumped from each bucket into the bins, the bucket was returned ot hte main cable and was sent on its way back to the Bingham terminal to be reloaded. The motion of hte entire four-mile cable could be arrested at either the Bingham or the Tooele terminals — or from three way-stations located along the route. The middle way-station located along hte route. The middle way-station was located on the very top of the Tooele terminal building and 1,450 feet above the loading station located at the Highland Boy Mine.”

Taken from “The Tooele Smelter” by Frank Dunlavy in Mining, Smelting and Railroading in Tooele County p 72-73