Shortly after start-up, it was apparent that it would be difficult to obtain the plant design throughput. The ore sample that had been used for grinding test work was found to be much softer than that of the orebody in depth. This had led the designers to design without a crushing stage and to designate … Read more
This Rod Mill —Ball Mill grinding team is in operation at a new 500 ton-per-day, base metal, selective flotation mill. Preliminary Grinding Tests Without Charge Mill size and specifications are determined by experienced engineers who study your grinding problem in detail and take into account the effect of grinding on your total milling circuit. Laboratory … Read more
First, let us look at the mill itself. Fig. 1 shows that there are four basic components – The shell, the heads, the ring gear and the trunnions. The heads are usually bolted to the shell. The trunnions are secured to the heads by bolts or made integrally with the head. The ring gear is … Read more
The “best” control strategy for a given plant is the strategy that most closely fulfills the overall operating objectives. The best strategy will likely not be “optimum” for any given specific goal but rather will involve a series of trade-offs made in consideration of the many factors that influence the operation in any significant way. … Read more
During the last few years, one of the great problems in the milling of all ores has been that of grinding. This subject involves not merely the cost of the operation, but also the selection of the proper degree and character of grinding to yield the best metallurgical results on the given ore. Considering the … Read more
In the previous discussion the fact was established that the work done by a ball when it strikes at the end of its parabolic path is proportional to its weight and velocity; then, since the velocity may be considered as constant for all the balls in the mill, the work done by a ball is … Read more
Testing Plant Equipment: In order to determine, among other things, the operating conditions of the ball-mill when working on this rock, a test mill of about 300 T. daily capacity was erected at Duluth, Minn. The fine-crushing plant contains a Hardinge 8-ft. by 22-in. (2.4-m. by 55.8-cm.) conical mill, a 6- by 27-ft. (1.8 by 8.2-m.) … Read more
These notes are based on observations made while on a recent trip through the West, for the purpose of studying the practical operation of the ball mill. The writer takes this opportunity to express his thanks for courtesies extended at the many plants visited as well as for the valuable data received. While there are … Read more
The following conclusions on the work of the Hardinge mill are based on data furnished to the writer by the Hardinge Conical Mill Co. in the form of the mesh cards hereto appended. Energy units (E. U.) and relative mechanical efficiencies (R. M. E.) are computed by the “volume method” of Stadler. Screen apertures used … Read more
In view of the prominence which the conical mill has attained in the fine-crushing field within the few years since its introduction, the following comparison with its more mature forerunner, the Chilean mill, based on extensive tests, is submitted in the interest of the milling profession. Soon after designing the concentrating plant, the conical Ball mill … Read more