Derniers chiffres du Coronavirus issus du CSSE 10/07/2021 (samedi 10 juillet 2021). Au niveau mondial le nombre total de cas est de 186067870, le nombre de gurisons est de 122465471, le nombre de dcs est de 4019050. Le taux de mortalit est de 2,16%, le taux de gurison est de 65,82% et le taux de personnes encore malade est de 32,02% Pour consulter le dtail d'un pays, cliquez sur l'un d'entre eux dans le tableaux ci-dessous. Vous trouverez des graphiques sous le tableau par pays et le tableau de l'volution mondiale jour par jour sous ces graphiques.
- Toutes les donnes affiches sur le site vous sont proposes des fins statistiques et titre d'information -- Elles proviennent toutes de donnes publiques disponibles en OpenData - -0,27 sec-
The basic parameters used in ball mill design (power calculations), rod mill or anytumbling millsizing are; material to be ground, characteristics, Bond Work Index, bulk density, specific density, desired mill tonnage capacity DTPH, operating % solids or pulp density, feed size as F80 and maximum chunk size, productsize as P80 and maximum and finally the type of circuit open/closed you are designing for.
In extracting fromNordberg Process Machinery Reference ManualI will also provide 2 Ball Mill Sizing (Design) example done by-hand from tables and charts. Today, much of this mill designing is done by computers, power models and others. These are a good back-to-basics exercises for those wanting to understand what is behind or inside the machines.
W = power consumption expressed in kWh/short to (HPhr/short ton = 1.34 kWh/short ton) Wi = work index, which is a factor relative to the kwh/short ton required to reduce a given material from theoretically infinite size to 80% passing 100 microns P = size in microns of the screen opening which 80% of the product will pass F = size in microns of the screen opening which 80% of the feed will pass
Open circuit grinding to a given surface area requires no more power than closed circuit grinding to the same surface area provided there is no objection to the natural top-size. If top-size must be limited in open circuit, power requirements rise drastically as allowable top-size is reduced and particle size distribution tends toward the finer sizes.
A wet grinding ball mill in closed circuit is to be fed 100 TPH of a material with a work index of 15 and a size distribution of 80% passing inch (6350 microns). The required product size distribution is to be 80% passing 100 mesh (149 microns). In order to determine the power requirement, the steps are as follows:
The ball mill motorpower requirement calculated above as 1400 HP is the power that must be applied at the mill drive in order to grind the tonnage of feed from one size distribution. The following shows how the size or select thematching mill required to draw this power is calculated from known tables the old fashion way.
The value of the angle a varies with the type of discharge, percent of critical speed, and grinding condition. In order to use the preceding equation, it is necessary to have considerable data on existing installations. Therefore, this approach has been simplified as follows:
A = factor for diameter inside shell lining B = factor which includes effect of % loading and mill type C = factor for speed of mill L = length in feet of grinding chamber measured between head liners at shell- to-head junction
Many grinding mill manufacturers specify diameter inside the liners whereas othersare specified per inside shell diameter. (Subtract 6 to obtain diameter inside liners.) Likewise, a similar confusion surrounds the length of a mill. Therefore, when comparing the size of a mill between competitive manufacturers, one should be aware that mill manufacturers do not observe a size convention.
In Example No.1 it was determined that a 1400 HP wet grinding ball mill was required to grind 100 TPH of material with a Bond Work Index of 15 (guess what mineral type it is) from 80% passing inch to 80% passing 100 mesh in closed circuit. What is the size of an overflow discharge ball mill for this application?
The 4th generation dynamic classifier XP4i has been introduced to the cement world market by Magotteaux, in order to have a better compact and energy efficient solution for existing circuit revamping or closing.
This ultimate classifier XP4i is now fitted with an integrated cyclone and recirculation fan inside its patented design body, a perfect combination between the compactness of a 1st generation and the efficiency of a 3rd generation classifier.Get in Touch with Mechanic