INTRODUCTION

Stone Crushing Industry is an important industrial sector in the country engaged in producing crushed stone of various sizes depending upon the requirement which acts as raw material for various construction activities such as construction of Roads, Highways, Bridges, Buildings, Canals etc. It is estimated that there are over 12,000 stone crusher units in India. The number is expected to grow further keeping in view the future plans for development of infrastructure of roads, canals and buildings that are required for overall development of the country. In India, the Stone Crushing Industry sector is estimated to have an annual turnover of Rs. 5000 crore (equivalent to over US$ 1 billion) and is therefore an economically important sector. The sector is estimated to be providing direct employment to over 500,000 people engaged in various activities such as mining, crushing plant, transportation of mined stones and crushed products etc. Most of these personnel are from rural and economically backward areas where employment opportunities are limited and therefore it carries greater significance in terms of social importance in rural areas. It is a source of earning for uneducated poor unskilled rural people.

The stone crusher is one such industry that exists in the vicinity of almost all major cities/towns throughout the country in all the states because the construction activities go on throughout the country. As transportation of stone over long distances adds to cost of the crushed stone products, the crushers need to be necessarily located nearer to the demand centers such as Cities, Bridges, Canals etc. Stone Crushers also need electricity supply and large number of man power for its operation. It also needs access roads for the movement of mined stone as well as crushed stone products. It is for these reason that most Stone Crushers are located along the periphery of Cities or in the vicinity of major construction projects. In most cases the Stone Crushers come up in clusters of number of units ranging from five to fifty in one cluster. The crushers are located nearer to the source of raw material such as Stone mines, River Beds etc. These stone crushers though socio-economically an important sector, gives rise to substantial quantity of fine fugitive dust emissions which create health hazards to the workers as well as surrounding population by way of causing respiratory diseases. The dust also adversely affects visibility, reduces growth of vegetation and hampers aesthetics of the area. In order to prevent/control these emissions, CPCB has already evolved Emission Standards and guidelines in 1989, which has been notified under Environment (Protection) Act, 1986 by Ministry of Environment & Forests vide Notification No. G.S.R. 742(E) dated 30th August 1990 & S.O. 8(E) dated December 31, 1990 based on techno-economic feasibility to achieve the standards. But over the years, as the need for more effective control and enforcement has been felt and to provide more specific guidelines to Comprehensive Industry Document on Stone Crushers

the stone crushers to enable them control emissions satisfactorily, CPCB has signed a Memorandum of Undertaking (MoU) with National Productivity Council (NPC) and commissioned the study with the work of reviewing the existing standards, guidelines and sitiing criteria and to evolve a Comprehensive Industry Document (COINDS) for Stone Crushers. This report is an outcome of the in-depth studies carried out by NPC jointly with CPCB on a representatives cross section of Stone Crushers throughout the country and a series of meeting held with State Pollution Control Boards, Stone Crushers Associations / Stone Crushers unit representatives etc..

Crushing Technologies

Various types of crushers are used in the stone crushing industry such as Jaw Crushers, Roller Crushers, Cone Crushers, Impactor, Rotopoctor etc. Generally, only Jaw crushers are used as Primary crushers. For secondary and tertiary crushing application either of Jaw, cone, roller, Impactor or Rotopoctor type crushers are used. Various types of crushers are briefly described below. I) Jaw Crushers: These are the oldest type of and most commonly used crushers in use and have changed little from the original design. In Jaw Crusher the feed is compressed between a stationary and a movable surface. A few of common types of Jaw crushers, in use, are described below. • Double Toggle Crusher: The Blake jaw crusher has a fixed jaw and a moving jaw pivoted at the top. The crushing faces themselves are formed either of manganese steel or of chilled cast iron. The maximum pressure is exerted on the large material, which is introduced at the top. These crushers are made with jaw widths varying from about 2” to 48” and the running speed varies from about 100 to 400 RPM. Comprehensive Industry Document on Stone Crushers • Single toggle Jaw crusher: The single-toggle crusher is the simplest and the lightest of the jaw crushers but is suitable only for producing low crushing forces and therefore